Re: RS-232 Tx / Rx monitoring LEDs?

[drlegendre .]

I've also seen C-R series voltage dropping circuits, here & there.

Correct me if I'm wrong, but doesn't the series cap dissipate power just as
it would, were it a series resistor? I mean, if the LED is passing 20mA,
the cap is also doing 20mA - and at whatever the Vdrop is.

Right? If not, why?

On Sun, Aug 23, 2015 at 1:17 AM, Chuck Guzis  wrote:

> On 08/22/2015 10:23 PM, dwight wrote:
>
> I would think the reverse voltage sum of the diodes is enough.
>> Different diodes also can handle different voltages. Since the sum
>> of the forward voltages is enough to handle AC, I'd suspect the
>> reverse voltages each would handle is quite small as well.
>> The problem is when the current limiting is done with a resistor
>> that in the forward direction drops a lot of voltage.
>> The diode has to handle the voltage until breakdown when reversed.
>> If the resistor was handling 1 Watts, with the right break down,
>> the LED could be taking .5 Watts. This is more than most are designed
>> for.
>>
>
> ...and that's just the nub of it.  The success of this depends largely on
> the consistent characteristics of every LED in the string.  Since LEDs tend
> to fail short if submitted to overvoltage, I've often wondered if a spike
> in the AC supply would precipitate a cascade failure in the string.  I've
> looked hard and there are no rectifier diodes in the string--just the LEDs
> themselves.  Probably saves about 5 cents or so of manufacturing cost.
>
> I've also seen LED "night lights" from China that employ nothing more than
> a safety capacitor (usually about 104) in series with a resistor connected
> to two back-to-back LEDs, all across the AC line.
>
> I've wondered what the lifetime of such a setup is.
>
> --Chuck.
>

Re: A tale of woe, including carelessness, stupidity and laziness....

[drlegendre .]

On Sat, Aug 22, 2015 at 11:44 PM, tony duell 
wrote:

>
> I have heard similar warnings about working on cars while wearing
> rings, or worse a wristwatch with a metal strap. A car battery can provide
> many hundreds of amps for a short period.
>
>
My cousin (who is a seasoned vehicle tech) once made the "car battery
positive to fenderwell via wristwatch" mistake.

He said the band went almost white hot before he was able to a) realize it
and b) break away. Second and third-degree to his wrist.

RE: Reversed Electrolytics redux

[Dave G4UGM]

> 
> Also, I now know why the +5 V is high.  It has a UA 7805 3 terminal
regulator
> serving as a voltage reference for a TIP-3055 so the supply can provide
more
> current.  That 7805 has a forward biased diode between the center terminal
> and ground, thus raising the output voltage by right around 0.5v.  I
expect I
> will leave it alone.


When used as series pass transistor the TIP-3055 will usually drop 0.6v
across the emitter under any significant load. Adding a silicon diode in the
7805 base is the normal fix...

http://www.bristolwatch.com/ele/basic_power_supplies.htm

> 
> The same design is used for the +24V, which comes out at 24.2V.
> 
> So, odds are that this supply could drive two floppy drives.
> 
> JRJ
> 
> 
> JRJ

Re: Reversed Electrolytics redux

[Jay Jaeger]

I figured as much.  And, with a 10K ohm bleeder resistor that I added on
the output (another added safety feature), the voltage dropped down to
5.2 and change - within spec.

JRJ

On 8/22/2015 6:19 PM, Dave G4UGM wrote:
>>
>> Also, I now know why the +5 V is high.  It has a UA 7805 3 terminal
> regulator
>> serving as a voltage reference for a TIP-3055 so the supply can provide
> more
>> current.  That 7805 has a forward biased diode between the center terminal
>> and ground, thus raising the output voltage by right around 0.5v.  I
> expect I
>> will leave it alone.
> 
> 
> When used as series pass transistor the TIP-3055 will usually drop 0.6v
> across the emitter under any significant load. Adding a silicon diode in the
> 7805 base is the normal fix...
> 
> http://www.bristolwatch.com/ele/basic_power_supplies.htm
> 
>>
>> The same design is used for the +24V, which comes out at 24.2V.
>>
>> So, odds are that this supply could drive two floppy drives.
>>
>> JRJ
>>
>>
>> JRJ
> 
> 

RE: VT100 preventative maintenance?

[tony duell]

> > ...
> > [1] In the UK we call all CRT elecrodes after the control grid (first grid) 
> > 'anodes' which
> > makes sense as they are run +ve wrt the cathode.
> 
> So does a UK tetrode have one grid and two anodes?  Or is there one 
> terminology for
>  CRTs and a different one for other tubes?

The second. A Tetrode over here has 2 grids (control grid and screen grid [1]) 
and one anode. A 
pentode has 3 grids (control, screen, supressor)

[1] An old name for a tetrode or pentode over here is a 'Screen grid valve' 
Some early valves 
had type codes which clearly came from this For example there was a 'AC/SG' 
which was 
an indirectly heated (the 'AC' part, meaning the heater could run on AC) 
tetrode (the 'SG'
part). I have an old Cossor MVS/PEN valve. That stands for 'Metalised' (meaning 
there is
a conductive coating on the outside of the glass envelope for shielding), 
Variable Mu
(non-linear, so amplification depends on grid bias) Screengrid (a tetrode or 
pentode) and
the 'PEN' part means it really is a Pentode.

Also note that we use the term 'valve' for  diodes, triodes, etc, but 'tube' 
for CRTs, nixie tubes,
dekatrons, voltage stabilisers, probably trochotrons, etc. There seems to be no 
obvious
reason for what is a 'valve' and what is a 'tube'.

-tony



paul

Reversed Electrolytics redux

[Jay Jaeger]

On 8/22/2015 2:41 PM, Jay Jaeger wrote:

> 
> Unfortunately, bearings did not help the floppy drive, so now I am busy
> taking the floppy power supply I got with my FD 100-8, making sure it is
> up to spec to use with the Shugart (and correcting that if needs be),
> and making it safer (mains fuse, switch) and more fault tolerant (fuse
> in the 24V line, at least) and making sure all of the mains connected
> innards are not exposed.  Just about done with that.  The +24V and -7 to
> -16V are in spec, but the +5V (which, curiously for a 1A supply, does
> NOT use a simple 3 terminal regulator) is a tad high, at 5.35V.  I may
> just change it to use a three terminal unit.
> 

Well, just found another reversed electrolytic - but this time the
original fault was not my own.  I decided to trace out this floppy
supply I have had for decades (back in my original Altair days), that I
got from the same guy from whom I purchased my Siemens FDD 100-8, and
discovered that the electrolytic on the unregulated -7 to -16 V was
reversed - installed BACKWARDS.  That capacitor is now in "reform
school".  ;)

Also, I now know why the +5 V is high.  It has a UA 7805 3 terminal
regulator serving as a voltage reference for a TIP-3055 so the supply
can provide more current.  That 7805 has a forward biased diode between
the center terminal and ground, thus raising the output voltage by right
around 0.5v.  I expect I will leave it alone.

The same design is used for the +24V, which comes out at 24.2V.

So, odds are that this supply could drive two floppy drives.

JRJ


JRJ

Re: RS-232 Tx / Rx monitoring LEDs?

[Chuck Guzis]

On 08/22/2015 10:23 PM, dwight wrote:


I would think the reverse voltage sum of the diodes is enough.
Different diodes also can handle different voltages. Since the sum
of the forward voltages is enough to handle AC, I'd suspect the
reverse voltages each would handle is quite small as well.
The problem is when the current limiting is done with a resistor
that in the forward direction drops a lot of voltage.
The diode has to handle the voltage until breakdown when reversed.
If the resistor was handling 1 Watts, with the right break down,
the LED could be taking .5 Watts. This is more than most are designed
for.


...and that's just the nub of it.  The success of this depends largely 
on the consistent characteristics of every LED in the string.  Since 
LEDs tend to fail short if submitted to overvoltage, I've often wondered 
if a spike in the AC supply would precipitate a cascade failure in the 
string.  I've looked hard and there are no rectifier diodes in the 
string--just the LEDs themselves.  Probably saves about 5 cents or so of 
manufacturing cost.


I've also seen LED "night lights" from China that employ nothing more 
than a safety capacitor (usually about 104) in series with a resistor 
connected to two back-to-back LEDs, all across the AC line.


I've wondered what the lifetime of such a setup is.

--Chuck.

RE: RS-232 Tx / Rx monitoring LEDs?

[dwight]

> From: ccl...@sydex.com
> 
> On 08/21/2015 08:36 AM, dwight wrote:
> > I was going to add something but it has already been said several
> > times. I will add that if using a LED on an AC like signal of high
> > voltage, one should use a diode. I recommend using a shunt diode
> > rather than a series diode when high voltages are being dropped by
> > the resistor. It reduces the need for a high voltage diode but makes
> > the resistor hotter. Some red LEDs glow orange when not protected
> > from 12VAC. You can ask how I know. Dwight
> 
> Ever take a close look at a string of Christmas-tree LEDs?  Most are 
> composed of a string of LEDs  hooked directly across the AC line--no 
> rectifier diode to be found.
> 
> Some seek to reduce the 60Hz flicker by employing two strings to 
> illuminate on both half-cycles, reducing the flicker somewhat.   Since 
> my eyes react to the flicker (it's like ants crawling over the string), 
> I found that simply employing a full-wave bridge rectifier can reduce 
> the appearance of flicker tremendously.
> 
> --Chuck

I would think the reverse voltage sum of the diodes is enough.
Different diodes also can handle different voltages. Since the sum
of the forward voltages is enough to handle AC, I'd suspect the
reverse voltages each would handle is quite small as well.
The problem is when the current limiting is done with a resistor
that in the forward direction drops a lot of voltage.
The diode has to handle the voltage until breakdown when reversed.
If the resistor was handling 1 Watts, with the right break down,
the LED could be taking .5 Watts. This is more than most are designed
for.
Dwight
 
  

RE: VT100 preventative maintenance?

[tony duell]

> > Also note that we use the term 'valve' for  diodes, triodes, etc, but
> > 'tube' for CRTs, nixie tubes, dekatrons, voltage stabilisers,
> > probably trochotrons, etc.  There seems to be no obvious reason for
> > what is a 'valve' and what is a 'tube'.

> Based on your examples, it sounds to me as though a "valve" is a vacuum
> device whose major purpose is to control current flowing elsewhere in
> its circuit, whereas a "tube" is anything else - a CRT's major purpose

Possibly. But diodes are normally called 'valves' over here, in fact I think
the term 'valve' came from the fact that a diode acts like the one-way
valve, say on a tyre. And not necessarily vacuum devices. Thyratrons
(gas filled triodes) are 'valves'. So is the infernal 0Z4 :-). But not voltage
stabilisers.

I am trying to think what we call tuning indicators -- magic eyes and the
like. Probably valves (even though they don't control anything and are
display devices).

> is display, with the current flow incidental to that; Nixies,
> dekatrons, and voltage stabilizers are cold-cathode gas-filled devices.
> A trochotron...that's an interesting case.  On the above (speculative)
> basis I could argue for either "valve" or "tube".

> Incidentally, thank you for mentioning trochotrons.  I was not
> previously aware of them, and now that I've read up on them a tiny bit
> I'm glad I have.

I wonder if they were ever used in early computers. Dekatrons were, both
in the Harwell Dekatron machine, and in some Anita calculators. But I've
only come across trochotrons in digital voltmeters and the like.

-tony

RE: A tale of woe, including carelessness, stupidity and laziness....

[tony duell]

> 
> The engineer said that it wasn't a problem because the highest voltage
> on the backplane is 5V. The manager pointed out that the power supply
> was rated for 600A, and undoubtedly could source more than that
> briefly, and to think about what would happen to your finger if you
> had hundreds of amps flowing through the ring.

I have heard similar warnings about working on cars while wearing 
rings, or worse a wristwatch with a metal strap. A car battery can provide
many hundreds of amps for a short period.

-tony

Re: (OT?) Copyright and IP

[drlegendre .]

"This goes directly against how information
behaves, which is to flow freely. "

Information has neither preference nor intent, nor any other inherent
behavioral characteristic(s).

You could make a water or electricity analogy - but both of those are most
often regulated, channeled, stored-up and rationed-out out as needed.

As much as I find appeal in the notion that "Information wants to be free",
information, per se, cannot want for anything at all.



On Sat, Aug 22, 2015 at 7:13 AM, Alexis Kotlowy <
thrashb...@kaput.homeunix.org> wrote:

> Hi List,
>
> This relates to the ongoing discussion about vintage computer software
> copyright.
>
> A year or so ago I did some Beta videotape backups for the Australian
> Computer Society. They're of keynote speeches at the 10th Australian
> Computer Conference in 1983. One that I'd like to mention is by Tania
> Amochev from (then) Control Data Corporation, titled Information
> Services of the Future.
>
> In it, things we now call data mining and Google AdSense are discussed,
> and the potential of data services in general (this is in 1983). One
> thing that struck me was the contrast between traditional copyright of
> material items, and how such ideas don't apply very well to non-material
> information.
>
> I was left with the impression that the idea of "Intellectual Property"
> is in some ways an attempt to force information to be treated like
> materials, which is an easy way to put a value information, but also
> allows it to be hoarded. This goes directly against how information
> behaves, which is to flow freely. This free-flow of information allows
> more information to be derived or generated, enhancing productivity and
> overall knowledge.
>
> To quote: "Information is diffusive - it leaks. The more it leaks, the
> more of it there is. Information is aggressive, even imperialistic. It
> simply breaks out of its unnatural bonds, the bonds of secrecy in which
> 'thing minded' people try to lock it. So secrecy, property rights,
> confidentiality, all enshrined in Western thought and law, are not
> particularly effective restraints on information."
>
> This is not a cry to abolish copyright and intellectual property laws,
> but to highlight some of the inadequacies of the thought process behind
> these laws when dealing with high speed, global information.
>
> Does anyone have any thoughts? If there was a massive shift in the
> fundamental philosophy of how information should be valued, where would
> you like that shift to go? For example, is there a way to pay
> programmers and similar professions by the quality of their work, rather
> than just the number of lines of code they write. How do you measure the
> quality of information?
>
> I'll see if I can get permission to have the six keynote addresses put
> online, because they're all fascinating.
>
> Cheers,
>
> Alexis.
>
> P.S., if this is way off topic, my apologies.
>

Re: Sign magnitude, one's complement, two's complement

[Chuck Guzis]

On 08/22/2015 06:26 PM, Paul Koning wrote:
 than the usual rule).


I recall the "integer multiply" feature (i.e. optional) available
on the 6000.  IXi  Xj*Xk, but it didn't provide any more precision
than the usual unnormalized double-precision multiply  DXi  Xj*Xk,
but saved some time spent fiddling with exponent fields.


???  Never heard of any such thing.  IXi Xj*Xk is a defined opcode,
but it's simply a synonym for Dxi Xj*Xk.


Well, we were always the guinea pig for QSEs in SSD.  It's not described 
in the Cyber 70 docs, but we had Cybers fitted with the option.  It did 
make its way into the 170s however:


In 60456100A, re: the 42 instruction (page 4-24, second column):

"This instruction is used in multiple-precision floating-point 
calculations.  This instruction also provides for integer multiplication 
capabilities where both operands have an exponent value of plus or minus 
zero and neither coefficient has been normalized.  The integer result 
sent to Xi is *48 bits with a 60-bit sign extension* (emphasis mine)."


A minor change that saved perhaps a few cycles.

Another oddball thing was then then-new Cyber 72/73 CMU.  An interesting 
beast, but not present on the 74.


It was possible initially to write code with the 46xxx CMU instruction 
in first 2 parcels of an instruction word.  All Cyber 73 CMU 
instructions were 60 bits, you could pack a call to a subroutine to do 
the equivalent thing in the lower 30 bits for the 74.  Worked pretty 
cool until the 170.  There, different models supported different subsets 
of CMU instructions (or not at all)--and attempting to execute one not 
implemented was greeted with an error stop.  The 170 people really 
screwed that one up.


--Chuck

RE: Silent 785 docs?

[Jay West]

Glen wrote...
-
Is that the one you rescued from somewhere in LA? Was wondering if you were 
able to successfully manage that.
-
Nope. That was an 800 series KSR. I still want that, but the business trip I 
was hoping to use to justify it never materialized. Still looking for someone 
in NO to pick up and ship, or at least hold for me.

The 785 I have had for decades. I think it came out of a rescue I did with Guy 
in Oklahoma.

J

Re: Silent 785 docs?

[Glen Slick]

On Sat, Aug 22, 2015 at 9:08 AM, Jay West  wrote:
> I've got a TI Silent 785 I'm trying to get configured/running.

Is that the one you rescued from somewhere in LA? Was wondering if you
were able to successfully manage that.

Re: 9-Track 1/2" Tape Drive Recommendations?

[Chuck Guzis]

On 08/22/2015 02:14 PM, Al Kossow wrote:



No, I haven't the faintest idea where you would even find a copy today.


I did find a reference to the CCVS suite of tests for sequential I/O:

http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA019757

TOG lists the 1985 suite as the standard validation for COBOL, but the 
link goes to NCC and thence to a 404.


One used to be able to get such stuff from the USDOC, but I doubt that 
they would know what you were talking about today.


I suspect that there's a reel of tape somewhere with the damned things 
on it.


--Chuck

Re: Sign magnitude, one's complement, two's complement

[Paul Koning]

> On Aug 22, 2015, at 9:15 PM, Chuck Guzis  wrote:
> 
> On 08/22/2015 04:40 PM, Paul Koning wrote:
>> 
>>> On Aug 22, 2015, at 6:27 PM, Chuck Guzis  wrote:
>>> 
>>> ...FLoating point can engender some interesting representations.
>>> Consider the exponent field on the aforementioned CDC 6000 series.
>>> It's a "biased by 2000 octal) system--and the assumed binary point
>>> of the mantissa is to the right of the LSB.  So, 2000  
>>>  0001 octal = 1 exactly.
>> 
>> EL-X8 doesn't use the bias, so the floating point representation of
>> an integer under 2^39 is the same as the integer representation.  And
>> the rule for normalizing float values preserves that (normalization
>> makes the exponent as close to zero as possible -- rather different
>> than the usual rule).
> 
> I recall the "integer multiply" feature (i.e. optional) available on the 
> 6000.  IXi  Xj*Xk, but it didn't provide any more precision than the usual 
> unnormalized double-precision multiply  DXi  Xj*Xk, but saved some time spent 
> fiddling with exponent fields. 

???  Never heard of any such thing.  IXi Xj*Xk is a defined opcode, but it's 
simply a synonym for Dxi Xj*Xk.

paul

RE: Silent 785 docs?

[Jay West]

I had written

Anyone have operators and/or service manual for the Silent 785?


Still looking for the manual, but... found a quick reference guide inside
the unit. I had seen it before, but didn't see the note on the back at the
bottom regarding configuration. Long story short, by default it uses the
acoustic coupler rather than the db25 on the back. I'll record it here for
posterity, since I don't see any docs on this unit online at all.

The incantation is:
CMD key, C for config mode and you get a question mark. You type your option
followed by return. To exit config mode, hit enter to exit with report of
saved config, or hit reset key to exit with no report. Note, enter and
return are separate keys.

The options which made it use the db25 on the back:

Modem type:
111 = autoselect interface

Method:
13 = 103/113/212/3400/full-duplex

Speed:
21 = 110
22 = 200
23 = 300
24 = 600
25 = 1200
26 = 2400
28 = 9600
29 = 300/1200

Parity:
31 = odd, no check
32 = even, no check
35 = odd, check
36 = even, check
37 = mark no check
38 = space no check

Best,

J

Re: Sign magnitude, one's complement, two's complement

[Chuck Guzis]

On 08/22/2015 04:40 PM, Paul Koning wrote:



On Aug 22, 2015, at 6:27 PM, Chuck Guzis  wrote:

...FLoating point can engender some interesting representations.
Consider the exponent field on the aforementioned CDC 6000 series.
It's a "biased by 2000 octal) system--and the assumed binary point
of the mantissa is to the right of the LSB.  So, 2000  
 0001 octal = 1 exactly.


EL-X8 doesn't use the bias, so the floating point representation of
an integer under 2^39 is the same as the integer representation.  And
the rule for normalizing float values preserves that (normalization
makes the exponent as close to zero as possible -- rather different
than the usual rule).


I recall the "integer multiply" feature (i.e. optional) available on the 
6000.  IXi  Xj*Xk, but it didn't provide any more precision than the 
usual unnormalized double-precision multiply  DXi  Xj*Xk, but saved some 
time spent fiddling with exponent fields.  There was no corresponding 
Integer divide.  So the integer adds would give the usual 60 bits of 
precision, while the integer multiply gave 48.


On the other hand, the unnormalized integer mantissas could be very 
useful.  One such is an integer divide by a constant.  Good enough for 
small magnitude numbers.


All of that went out the window on the STAR, however.  A more 
traditional normalized two's complement format was used.


--Chuck

Re: 5.25 floppies that read but don't write

[Marc Verdiell]

> Do we know the make/model of this drive?
It's a Chinon FR-506 (NOT an FZ-506)

>On 5.25" HD drives, pin 2 is generally a drive *input*.  That is, the 
>host telegraphs what's needed, not the drive.

Indeed, you have to be careful to put the right media and issue the proper
density specific format command yourself, unless you work at the default of
the drive, which in this case is HD. But I did, and I double checked the
computer was outputting the right density signal on pin 2 on format and on
write. Unfortunately the drive didn't respond correctly for writes in any
settings I tried (auto or fixed density).

On reading, from what I saw, the computer (at least mine) just tries both
densities a couple times until it can read something. If there is some good
data it declares success and keeps the pin 2 at the level that works for the
rest of the session. There the news was better, the drive responded
correctly to the pin 2 when it was set in auto, but incorrectly when it was
in fixed HD (reading only in DD instead). So I left it in auto.

At this point I'll declare this drive non functional, though still OK as a
dual density, read-only drive... And look for a better HD one. My other
5.25" 360k DD 48tpi/300RPM drives read and write OK, so I have a working
solution at low density. I want to recreate LIF drives for HP's, writing DD
is what I need most anyhow. Thanks for the help, you pointed me in the right
direction each time.

Re: 9-Track 1/2" Tape Drive Recommendations?

[Glen Slick]

On Aug 22, 2015 1:08 AM, "Ali Fahimi"  wrote:
>
> Hello All,
>
> Recently I came across a complete Pertec interface (card, manual,
software,
> and, cables) thanks to list-member Shaun. Of course what is the point of
> having an interface if you have nothing to interface it to!

What controller did you get? Did you get original installation media for
the software?

I have some Computer Logics PCTD-16 controllers. One came installed in a PC
with some Chi DOS software for it on the the hard drive and manuals but no
installation floppies. I can just copy the installed software directory to
a different PC to move the controller but it would be nice to have a copy
of the original installation floppies to be able to do a clean standard
installation.

Re: Sign magnitude, one's complement, two's complement

[Paul Koning]

> On Aug 22, 2015, at 6:27 PM, Chuck Guzis  wrote:
> 
> ...FLoating point can engender some interesting representations.  Consider 
> the exponent field on the aforementioned CDC 6000 series.  It's a "biased by 
> 2000 octal) system--and the assumed binary point of the mantissa is to the 
> right of the LSB.  So, 2000    0001 octal = 1 exactly.

EL-X8 doesn't use the bias, so the floating point representation of an integer 
under 2^39 is the same as the integer representation.  And the rule for 
normalizing float values preserves that (normalization makes the exponent as 
close to zero as possible -- rather different than the usual rule).

paul

Re: VT100 preventative maintenance?

[Mouse]

> Also note that we use the term 'valve' for  diodes, triodes, etc, but
> 'tube' for CRTs, nixie tubes, dekatrons, voltage stabilisers,
> probably trochotrons, etc.  There seems to be no obvious reason for
> what is a 'valve' and what is a 'tube'.

Based on your examples, it sounds to me as though a "valve" is a vacuum
device whose major purpose is to control current flowing elsewhere in
its circuit, whereas a "tube" is anything else - a CRT's major purpose
is display, with the current flow incidental to that; Nixies,
dekatrons, and voltage stabilizers are cold-cathode gas-filled devices.
A trochotron...that's an interesting case.  On the above (speculative)
basis I could argue for either "valve" or "tube".

Incidentally, thank you for mentioning trochotrons.  I was not
previously aware of them, and now that I've read up on them a tiny bit
I'm glad I have.

/~\ The ASCII Mouse
\ / Ribbon Campaign
 X  Against HTMLmo...@rodents-montreal.org
/ \ Email!   7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B

Re: Sign magnitude, one's complement, two's complement

[Chuck Guzis]

On 08/22/2015 02:23 PM, Sean Conner wrote:


For my own morbid curiosity, and because it came up on another
mailing list I'm on [1], what machines commercially avaialble were
sign magnitude and one's complement?  Every machine I've encountered
was two's complement (okay, IEEE 754 [2] is a sign magnitude format
but I'm talking about integer implementations here, not floating
point).  I've only found reference to one sign magnitude computer
(the IBM 7090, release in 1959) and a few one's complement machines
(mostly the PDP series from DEC).

Where there others?  And honestly, are there any machines that use
anything other than two's complement today?


There were, as noted, several ones complement systems.

Every decimal computer that I can think of, or ones, at least that have 
a decimal instruction vocabulary are sign-magnitude.  That is, a 
negative one is represented as -1 in some form, not in its nine's or 
ten's complement.


For another pure binary sign-magnitude system, consider one of the first 
minicomputers (although the term hadn't been then invented)--the Packard 
Bell PB 250.  I'm pretty certain there were several others.


Floating point can engender some interesting representations.  Consider 
the exponent field on the aforementioned CDC 6000 series.  It's a 
"biased by 2000 octal) system--and the assumed binary point of the 
mantissa is to the right of the LSB.  So, 2000    0001 octal 
= 1 exactly.


--Chuck

Re: Sign magnitude, one's complement, two's complement

[Jon Elson]

On 08/22/2015 04:49 PM, Al Kossow wrote:

On 8/22/15 2:23 PM, Sean Conner wrote:


   For my own morbid curiosity, and because it came up on 
another mailing
list I'm on [1], what machines commercially avaialble 
were sign magnitude

and one's complement?


A table of what computers had what numeric representation 
is one of those things
that should have been done, but never has. Now that 
bitsavers has a reasonable collection

of technical/programming manuals, it might even be possible.

http://quadibloc.com/comp/cpint.htm

has some information, but it isn't really in any sort of 
tabular form.


AFAIK, the PDP-1 was the only DEC 1's compliment machine 
that shipped.



The LINC part of the LINC-8 and PDP-12 were one's complement.

Jon

Re: Sign magnitude, one's complement, two's complement

[Jon Elson]

On 08/22/2015 04:23 PM, Sean Conner wrote:

   For my own morbid curiosity, and because it came up on another mailing
list I'm on [1], what machines commercially avaialble were sign magnitude
and one's complement?  Every machine I've encountered was two's complement
(okay, IEEE 754 [2] is a sign magnitude format but I'm talking about integer
implementations here, not floating point).  I've only found reference to one
sign magnitude computer (the IBM 7090, release in 1959) and a few one's
complement machines (mostly the PDP series from DEC).


The LINC (Laboratory INstrument Computer) was one's 
complement, with a 12-bit word.  Several derivative machines 
were the same.  The most confusing, of course, were the 
LINC-8 and PDP-12, which had the PDP-8 instruction set with 
two's complement, and the LINC instruction set, with one's 
complement, all in the SAME machine. SHEESH!


Jon

Re: Sign magnitude, one's complement, two's complement

[Paul Koning]

> On Aug 22, 2015, at 5:49 PM, Al Kossow  wrote:
> 
> On 8/22/15 2:23 PM, Sean Conner wrote:
>> 
>>   For my own morbid curiosity, and because it came up on another mailing
>> list I'm on [1], what machines commercially avaialble were sign magnitude
>> and one's complement?
> 
> A table of what computers had what numeric representation is one of those 
> things
> that should have been done, but never has. Now that bitsavers has a 
> reasonable collection
> of technical/programming manuals, it might even be possible.
> 
> http://quadibloc.com/comp/cpint.htm
> 
> has some information, but it isn't really in any sort of tabular form.

Some comments on that data.

There are a bunch of one's complement machines.  CDC 6000 series has already 
been mentioned.  Electrological EL-X1 and EL-X8 are another example.

Both the CDC and the EL-X8 have another interesting property: the floating 
point format is one's complement, and the mantissa is an integer rather than a 
fraction.  F.E.K Kruseman Aretz in his paper on the EL-X8 floating point 
implementation calls this "Grau representation"  (A.A. Grau. On a 
floating–point representation for use with algorithmic languages. Comm. ACM 5 
(1962) 160.).  One's complement in the sense that negating a float was done 
exactly like negating an int: by complementing it.  And in the EL-X8 the 
exponent field was a one's complement integer also (unlike CDC where is's an 
excess-02000 value).

One interesting property of one's complement machines is whether they "prefer 
+0" or "prefer -0".  If you use an adder, then x+(-x) produces -0 -- the only 
way to get +0 is as the result of 0+0.  Cray apparently didn't like that, so 
the CDC 6000 series use a subtractor, so add is done as a-(-b).  If you do 
that, then  you get "prefer +0" -- x + (-x) is +0 if x is non-zero, and the 
only way to get a -0 result is to start with a -0 input.  But EL-X8 is "prefer 
-0".  I don't know about other one's complement machines.

> AFAIK, the PDP-1 was the only DEC 1's compliment machine that shipped.
> 
> I had also heard that 1's compliment never caught on in short word length
> machines because of the difficulty dealing with multi-word arithmetic.

Interesting point.  Not true for the CDC 6000 series PPUs because they had an 
18 bit accumulator, so a 24 bit add (which was fairly common) would look like:
ldm foo
adm bar
stm result
shn -12 shift carry into lower bits
adm foo+1
adm bar+1
stm result+1

As for sign/magnitude, there's the IBM 1620.  Not binary, but sign/magnitude 
decimal.

paul

Re: A tale of woe, including carelessness, stupidity and laziness....

[Jon Elson]

On 08/22/2015 02:41 PM, Jay Jaeger wrote:
Thanks. Really, such mistakes aren't too demoralizing if 
one can get the parts, get them in a reasonable amount of 
time, at a reasonable price, and have the skill to do the fix
One of the biggest oopses I ever had was I got a Memorex 10 
MB hard drive with SASI controller for my S-100 /CP/M 
system.  I had just gotten it very roughly working, when I 
was fiddling with something and the SASI controller touched 
the drive and there were sparks.  I did the finger test 
first, and replaced all chips that were sizzling hot.  Then, 
I went through, looking for bad logic levels, and replaced 
the chips driving those signals.  Then, when I still had bad 
logic levels, I replaced the chips receiving those signals.  
All the time I was worred that it might have popped one or 
more of the microcode ROMS.  Well, after some more 
replacing, it finally came back up, and the CP/M OS I had on 
the drive still worked!


I guess I've had a few more cases where something went poof, 
but that is one of the ones I still remember well.


Jon

Re: Sign magnitude, one's complement, two's complement

[Toby Thain]

On 2015-08-22 5:49 PM, Al Kossow wrote:

On 8/22/15 2:23 PM, Sean Conner wrote:


   For my own morbid curiosity, and because it came up on another mailing
list I'm on [1], what machines commercially avaialble were sign magnitude
and one's complement?


A table of what computers had what numeric representation is one of
those things
that should have been done, but never has. Now that bitsavers has a
reasonable collection
of technical/programming manuals, it might even be possible.

http://quadibloc.com/comp/cpint.htm

has some information, but it isn't really in any sort of tabular form.



Blaauw and Brooks also has a lot of the required data, not sure if it 
has a table.


There's a copy on ebay right now http://ur1.ca/nipwp

--Toby


AFAIK, the PDP-1 was the only DEC 1's compliment machine that shipped.

I had also heard that 1's compliment never caught on in short word length
machines because of the difficulty dealing with multi-word arithmetic.

Re: Sign magnitude, one's complement, two's complement

[Al Kossow]

On 8/22/15 2:23 PM, Sean Conner wrote:


   For my own morbid curiosity, and because it came up on another mailing
list I'm on [1], what machines commercially avaialble were sign magnitude
and one's complement?


A table of what computers had what numeric representation is one of those things
that should have been done, but never has. Now that bitsavers has a reasonable 
collection
of technical/programming manuals, it might even be possible.

http://quadibloc.com/comp/cpint.htm

has some information, but it isn't really in any sort of tabular form.

AFAIK, the PDP-1 was the only DEC 1's compliment machine that shipped.

I had also heard that 1's compliment never caught on in short word length
machines because of the difficulty dealing with multi-word arithmetic.

Re: Sign magnitude, one's complement, two's complement

[Jay Jaeger]

Univac 1100 series - one's complement.

On 8/22/2015 4:23 PM, Sean Conner wrote:
> 
>   For my own morbid curiosity, and because it came up on another mailing
> list I'm on [1], what machines commercially avaialble were sign magnitude
> and one's complement?  Every machine I've encountered was two's complement
> (okay, IEEE 754 [2] is a sign magnitude format but I'm talking about integer
> implementations here, not floating point).  I've only found reference to one
> sign magnitude computer (the IBM 7090, release in 1959) and a few one's
> complement machines (mostly the PDP series from DEC).  
> 
>   Where there others?  And honestly, are there any machines that use
> anything other than two's complement today?  
> 
>   -spc
> 
> [1]   http://lua-users.org/lists/lua-l/2015-08/msg00386.html
> 
> [2]   AKA floating point.
> 
> 

Re: Sign magnitude, one's complement, two's complement

[Toby Thain]

On 2015-08-22 5:23 PM, Sean Conner wrote:


   For my own morbid curiosity, and because it came up on another mailing
list I'm on [1], what machines commercially avaialble were sign magnitude
and one's complement?  Every machine I've encountered was two's complement
(okay, IEEE 754 [2] is a sign magnitude format but I'm talking about integer
implementations here, not floating point).  I've only found reference to one
sign magnitude computer (the IBM 7090, release in 1959) and a few one's
complement machines (mostly the PDP series from DEC).

   Where there others?  And honestly, are there any machines that use
anything other than two's complement today?


CDC 6000 series are significant one's-complement machines.

--Toby




   -spc

[1] http://lua-users.org/lists/lua-l/2015-08/msg00386.html

[2] AKA floating point.

Re: A tale of woe, including carelessness, stupidity and laziness....

[Jay Jaeger]

On 8/22/2015 4:11 PM, Eric Smith wrote:

> In my mostly misspent youth, I once had the opportunity to visit a
> facility where a now obscure supercomputer was developed. The product
> manager was showing me around.   

That wasn't Astronautics' ZS, by any chance?  I ask, because I know some
folks who worked on it and its software, and there are a couple of
interesting stories I know about their work environment.

I was surprised to find, via Google, that one of them still exists (at
RICM).

JRJ

Re: Larry Niven's Altair

[Fred Cisin]

On Sat, 22 Aug 2015, Tothwolf wrote:
Indeed. Apple even screwed up on this with their iconic rainbow apple logo. I 
discovered this while researching the history of the logo while doing image 
work on Wikipedia / Wikimedia Commons many years ago. It is still a 
trademark, but the image is public domain because it was published before 
1978 with no notice.

https://commons.wikimedia.org/wiki/File:Apple_Computer_Logo_rainbow.svg


Despite its lack of COPYRIGHTability, it is a REGISTERED TRADEMARK,
which is more important to protect for THAT.
(Either protection would make a competitor putting it on their 
products an infringement)

Sign magnitude, one's complement, two's complement

[Sean Conner]

  For my own morbid curiosity, and because it came up on another mailing
list I'm on [1], what machines commercially avaialble were sign magnitude
and one's complement?  Every machine I've encountered was two's complement
(okay, IEEE 754 [2] is a sign magnitude format but I'm talking about integer
implementations here, not floating point).  I've only found reference to one
sign magnitude computer (the IBM 7090, release in 1959) and a few one's
complement machines (mostly the PDP series from DEC).  

  Where there others?  And honestly, are there any machines that use
anything other than two's complement today?  

  -spc

[1] http://lua-users.org/lists/lua-l/2015-08/msg00386.html

[2] AKA floating point.

Re: 9-Track 1/2" Tape Drive Recommendations?

[Al Kossow]

On 8/22/15 11:43 AM, Chuck Guzis wrote:


Historically, the two are very different in application.  If you've got a COBOL 
handy on your tape system, try running the 1974 Navy Audit Tests, once the set 
of benchmarks by which CODASYL compliance
of a vendor's COBOL was judged. (Al, do you have a copy of those on bitsavers?)




No, I haven't the faintest idea where you would even find a copy today.

Re: A tale of woe, including carelessness, stupidity and laziness....

[Eric Smith]

On Sat, Aug 22, 2015 at 1:41 PM, Jay Jaeger  wrote:
> But the carelessness was DANGEROUS, which is really why I posted it.
>
> (BTW, in the way of other stories, a good friend once took out the
> processor UNIBUS interface and damaged peripherals when his watch
> shorted to the backplane of a PDP-11/20.  I also did something not too
> dissimilar with my ring shorting out one bus line on my PDP-8/L.  Sigh).

In my mostly misspent youth, I once had the opportunity to visit a
facility where a now obscure supercomputer was developed. The product
manager was showing me around. At one point we were looking at the
backplane of a machine being tested or debugged, and an engineer comes
over and starts to do something with the backplane, and the manager
grabs his hand. He tells the engineer that he shouldn't work on it
with a gold ring on his finger. At first I thought the manager was
worried about the possibility of damage to the machine, but he quickly
explained that he wasn't much worried about that, but rather for
employee safety.

The engineer said that it wasn't a problem because the highest voltage
on the backplane is 5V. The manager pointed out that the power supply
was rated for 600A, and undoubtedly could source more than that
briefly, and to think about what would happen to your finger if you
had hundreds of amps flowing through the ring.

I suppose that might not be quite as exciting as having your neck tie
caught in a 1403, but it still could make for a really bad day.

Re: Larry Niven's Altair

[Tothwolf]

On Thu, 20 Aug 2015, Paul Koning wrote:

On Aug 20, 2015, at 10:30 AM, Jay Jaeger  wrote:

On 8/20/2015 3:32 AM, Randy Dawson wrote:

I assume all the 8K, 4K BASICs are in public domain by now.  The demo 
for the kids will be the 15 minutes of paper tape, followed by READY.


Bad assumption.  Things that were actually registered even if there was 
no notice, or published with a copyright notice would still be 
protected under U.S. copyright.


Depending on when.  If it was published without notice, the key question 
is whether publication occurred before Jan 1, 1978, or after.  After, 
notice does not matter; before, lack of notice means no copyright.


Indeed. Apple even screwed up on this with their iconic rainbow apple 
logo. I discovered this while researching the history of the logo while 
doing image work on Wikipedia / Wikimedia Commons many years ago. It is 
still a trademark, but the image is public domain because it was published 
before 1978 with no notice.


https://commons.wikimedia.org/wiki/File:Apple_Computer_Logo_rainbow.svg

FS: PDP-11/55

[Guy Sotomayor]

I have nothing to do with this...I just noticed it on alt.sys.pdp11 and 
figured that I'd pass it along.


TTFN - Guy

   Hi all,

   I have a PDP-11/55 for sale (Ottawa, Ontario, Canada).  Bids open
   until 2015 09 15, buyer to arrange shipping, I will have it wrapped
   and ready to go.

   Please visit:

www.krten.com/~rk/museum/index.html

   For pictures, detailed inventory and contact info.  Sealed bids via
   eamil please.  Winner will be notified 2015 09 16, machine will be
   ready to ship same day.  Must be shipped / picked up no later than
   2015 10 09.

   Sold AS-IS / where is, untested, unpowered since received.
   Comes with H960 rack and 2 side panels.

   Cheers,
   -RK

   -- 
   Robert Krten


   Visit me at http://www.ironkrten.com

RE: De-yellowing

[Tothwolf]

On Sat, 22 Aug 2015, Dave G4UGM wrote:

On Sat, 22 Aug 2015, Pete Turnbull wrote:

On 22/08/2015 13:50, Tothwolf wrote:

On Sat, 22 Aug 2015, Dave G4UGM wrote:


All the techniques discussed so far involve using a "bleach" of some
kind and possibly UV light. Some use other materials so you have a
gell which makes it easier to apply.
From what I have read yellowing usually/often/always re-occurs..


Hydrogen Peroxide, not bleach.


Hydrogen peroxide *is* a bleach, as any chemist can tell you.  Never 
heard of "peroxide blonde"?


I should probably have said a ""peroxide based bleaching agent" as most 
folks assume "bleach" means "chlorine based bleach" which is not what is 
being used here.
However there are several variations on this theme and several slightly 
different chemicals have been used as the bleach...


Exactly what I meant. Most will assume chlorine based bleach when someone 
mentions the term "bleach".

RE: VT100 preventative maintenance?

[tony duell]

> 
> Oooh, didn't know about the diodes. Are there any specific ones that you

Err, no... There is this witch-hunt against capacitors, but other components are
never considered

> think should be replaced no matter what? If not, are there any tests you
> would recommend?

There are several supplies derrived from the flyback transformer. Let's take as 
an example the Ball Brothers VT100 monitor on page 43 of the printset on 
bitsavers.


There is a -120V line, used for the control grid (g1), produced from the primary
side of the flyback by CR110 and C117. I think if this failed it wouldn't 
damage the
flyback, though

There is a +32V supply for the video amplifier, produced by CR114 and C121
A 400V supply for the the first and focus anodes (OK, g2 and g3 across
the Pond [1]) -- CR113 and C120. If either of those play up in can cause the
flyback to overheat, 

The 11.5kV final anode voltage is produced by CR1 and smoothed by the
capacitance of the CRT. I think CR1 is integral with the flyback transformer
though.

[1] In the UK we call all CRT elecrodes after the control grid (first grid) 
'anodes' which
makes sense as they are run +ve wrt the cathode. In the states, everything 
between the
cathode and final anode (the aquadag coating on the CRT flare running at 10kV or
more) is a 'grid'. Now something has just struck me. The adjusment for the 
first anode, if present (it isn't in this VT100) is known as the 'screen' 
control. What I 
do not know is if it's called that because it controls the overall brightness 
of the CRT
screen, or because it sets the voltage on what is called G2 across the Pond, 
and which
 would be the screen grid of a tetrode or pentode. Does anyone know the reason?

-tony

Re: VT100 preventative maintenance?

[Paul Koning]

> On Aug 22, 2015, at 3:14 PM, tony duell  wrote:
> 
> ...
> [1] In the UK we call all CRT elecrodes after the control grid (first grid) 
> 'anodes' which
> makes sense as they are run +ve wrt the cathode. 

So does a UK tetrode have one grid and two anodes?  Or is there one terminology 
for CRTs and a different one for other tubes?

paul

VT100 preventative maintenance?

[Earl Evans]

Hi all,

I have two VT100 terminals. Both of them work just fine.

Should I leave well enough alone, or is there preventative maintenance that
should be done? For instance, should capacitors be proactively replaced. In
general, I'm thinking about things that, if they fail catastrophically,
would cause collateral damage.

Thanks!

- Earl

Re: VT100 preventative maintenance?

[Jarratt RMA]

Oooh, didn't know about the diodes. Are there any specific ones that you
think should be replaced no matter what? If not, are there any tests you
would recommend?

Regards

Rob

On 22 August 2015 at 19:10, tony duell  wrote:

> >
> > Should I leave well enough alone, or is there preventative maintenance
> that
> > should be done? For instance, should capacitors be proactively replaced.
> In
> > general, I'm thinking about things that, if they fail catastrophically,
> > would cause collateral damage.
>
> The main part you want to protect is the flyback transformer. It is very
> hard to
> get a good replacement now. Flybacks can just fail, but failure can be
> caused
> by defective diodes and capactors on the video PCB. Look at the schematics
> for
> your video board (there are at least 3 versions) for half-wave rectifier
> circuits that
> produce the CRT and video stage supply voltages from the flyback. You
> might want
> to check or replace those diodes and caps.
>
> A VT100 and models derived from it (VT105, etc) has an SMPSU. Defective
> capacitors
> on that can kill the chopper transistor, but that is in not impossible to
> replace.
>
> -tony
>
>

Re: VT100 preventative maintenance?

[Jarratt RMA]

I can't say I know for sure, but I did replace all the electrolytics on the
video control boards of both my VT101 and VT102, because there was a
definite wobble to the image on both terminals. Replacing all of them fixed
the wobble. As I have posted before, I did this after testing each
capacitor with the test equipment I have, which is just a capacitance meter
and an ESR meter, neither of which appeared to reveal a problem.

Regards

Rob

On 22 August 2015 at 18:52, Earl Evans  wrote:

> Hi all,
>
> I have two VT100 terminals. Both of them work just fine.
>
> Should I leave well enough alone, or is there preventative maintenance that
> should be done? For instance, should capacitors be proactively replaced. In
> general, I'm thinking about things that, if they fail catastrophically,
> would cause collateral damage.
>
> Thanks!
>
> - Earl
>

RE: VT100 preventative maintenance?

[tony duell]

> 
> Should I leave well enough alone, or is there preventative maintenance that
> should be done? For instance, should capacitors be proactively replaced. In
> general, I'm thinking about things that, if they fail catastrophically,
> would cause collateral damage.

The main part you want to protect is the flyback transformer. It is very hard 
to 
get a good replacement now. Flybacks can just fail, but failure can be caused
by defective diodes and capactors on the video PCB. Look at the schematics for
your video board (there are at least 3 versions) for half-wave rectifier 
circuits that 
produce the CRT and video stage supply voltages from the flyback. You might want
to check or replace those diodes and caps.

A VT100 and models derived from it (VT105, etc) has an SMPSU. Defective 
capacitors
on that can kill the chopper transistor, but that is in not impossible to 
replace.

-tony

Re: Larry Niven's Altair

[Robert Ferguson]

I have had several similar personal experiences. Even in the face of extreme 
need, huge companies and major institutions sometimes can't find things you'd 
think should be at their fingertips.

When you think about it from a historical point of view, it's actually pretty 
shocking.

> On Aug 21, 2015, at 12:50 AM, Eric Smith  wrote:
> 
>> On Thu, Aug 20, 2015 at 10:22 PM, Chuck Guzis  wrote:
>> Indeed, I've been contacted by an author for a copy of his own software to
>> be licensed to another party, as he'd lost the code several years back.
>> (Yes, I purchased a license way back when).
> 
> A few years ago, an engineer at a Very Big Corporation asked me if I
> had their source code to the firmware in one of their best-selling
> products, which has sold tens of millions of units over more than two
> decades.  They had lost the source code, and they knew that I had some
> familiarity with the internals of the product, so they thought I might
> have the source code.
> 
> I had actually requested the source code from them many years before,
> and had been willing to sign an NDA, but they had not been willing to
> make it available to me.
> 
> A few years after they asked me, they did track down one of the
> employees who originally wrote the firmware, and who had retained a
> copy of the source code, probably contrary to company policy.
> 
> I've worked for several companies that lost source code and were saved
> by employees having kept copies in violation of corporate policy. One
> of those companies threatened to fire the employee who saved their
> bacon by having kept the code. (No, it wasn't me.)
> 
> People have told me that big companies have good controls and don't
> lose their source code. From personal experience I can say that you
> can't count on that.

Re: A tale of woe, including carelessness, stupidity and laziness....

[Jay Jaeger]

On 8/22/2015 12:55 PM, Tapley, Mark wrote:

> Jay,
>   this is a really great post. I feel really bad for you - having the 
> same piece of equipment go bang/flash more than once would have been totally 
> demoralizing to me - but I really admire both your tenacity and your 
> willingness to share this with the rest of us. 
>   Thank you! Sure hope that disk is spinning its proper string of bits 
> before long. You deserve the chance to post a victory story soon!
>   
> - Mark
> 

Thanks.  Really, such mistakes aren't too demoralizing if one can get
the parts, get them in a reasonable amount of time, at a reasonable
price, and have the skill to do the fix (which, in this case, wasn't a
whole lot) -- especially if there are good lessons to be learned along
the way.

But the carelessness was DANGEROUS, which is really why I posted it.

(BTW, in the way of other stories, a good friend once took out the
processor UNIBUS interface and damaged peripherals when his watch
shorted to the backplane of a PDP-11/20.  I also did something not too
dissimilar with my ring shorting out one bus line on my PDP-8/L.  Sigh).

Unfortunately, bearings did not help the floppy drive, so now I am busy
taking the floppy power supply I got with my FD 100-8, making sure it is
up to spec to use with the Shugart (and correcting that if needs be),
and making it safer (mains fuse, switch) and more fault tolerant (fuse
in the 24V line, at least) and making sure all of the mains connected
innards are not exposed.  Just about done with that.  The +24V and -7 to
-16V are in spec, but the +5V (which, curiously for a 1A supply, does
NOT use a simple 3 terminal regulator) is a tad high, at 5.35V.  I may
just change it to use a three terminal unit.

Once I get that together, I can try out my SA-801's to see if that was
what blew the Altos power supply up, or if it just shorted against
something when I started that test.  I can also more easily then measure
the "wobble" on the SA-800 and compare it to other drives, swap out
spindles, etc.

JRJ

Re: De-yellowing

[Chuck Guzis]

On 08/22/2015 12:11 PM, Terry Stewart wrote:


In my experience deyellowing is only temporary
http://www.classic-computers.org.nz/blog/2013-01-15-retr0bright-only-temporary.htm

 It does make the cases look good for a while though. (:


I can believe that the effect is only temporary--the action simply 
cannot go any deeper than a few microns.  All of which goes to show that 
if you want a more permanent color, there's always paint.  I have 
equipment that's made from high-density polyurethane foam (no special 
dies or forms needed for injection molding) finished with a coat of 
paint that's more than 30 years old.  It looks as good as the day it was 
delivered.


--Chuck

RE: De-yellowing

[Ali]

> I've never tried the stuff - but is it a permanent fix, or does the
> yellowing gradually come back?

It comes back. Search for retrobright on VCF. Tez has posted pictures of his
experience.

-Ali

Re: De-yellowing

[Terry Stewart]

>Has anyone tried ditching the peroxide and simply gone to using a solution
of sodium percarbonate (e.g. "Oxyclean")?
>Cheap and pretty shelf-stable in the powder form

Yes, I have Chuck.
http://www.classic-computers.org.nz/blog/2011-01-21-deyellowing-with-oxy-only.htm

Sometimes it doesn't turn out well though...
http://www.classic-computers.org.nz/blog/2011-04-11-lisa-keys-retrobrighting-misstep.html

With my own retr0briting I've found off-white cream cases come up well, but
anything that is grey can easily "bloom" if over exposed.

In my experience deyellowing is only temporary
http://www.classic-computers.org.nz/blog/2013-01-15-retr0bright-only-temporary.htm

It does make the cases look good for a while though. (:

Terry (Tez)

Re: De-yellowing

[Jerry Kemp]

All, the original page seems to be off line currently for retr0bright.

Also, more current copies seem to be forbidden to be archived via robots.txt.

Here is an older copy of the page that was available in the Wayback Machine.

enjoy,

Jerry

Re: More on manuals plus rescue

[Robert Johnson]

Sean,

Avaya for a while in the early to mid 2000's only made their manuals  
available to authorized resellers, that seems to have changed sometime  
after buying Nortel, all of the Avaya manuals, and the corresponding  
nortel ones became freely available online. Not sure I have the link  
anymore however. I personally find the Meridian much easier to program  
than say a Merlin II or whatever - but I found I needed a manual in  
either case to not be completely lost.


Robert Johnson
--
Gtalk/Jabber:al...@blastpuppy.com
AIM:AlohaWulf
Yahoo:AlohaWulf
Skype:AlohaWolf
Telephone:+1-562-286-4255
C*NET: 18219881
Email:al...@blastpuppy.com
Email:alohaw...@gmail.com
--
"Follow the path of the unsafe, independent thinker. Expose your ideas  
to the danger of controversy. Speak your mind and fear less the label  
of "crackpot" than the stigma of conformity."


- Thomas J. Watson Sr.



On 21-Aug-15, at 12:00 PM, Sean Caron wrote:

That's odd, as long as I can remember, Lucent/Avaya distributed the  
manuals
at least for their PBX and key products pretty openly; Nortel tried  
to keep
them more closely held but eventually relented, too. Carrier-grade  
stuff
(i.e. 5ESS and SL-100/DMS-100) was always another story, of course.  
I don't
recall ever having any issues getting needed documentation when  
bringing my
Definity up and that was circa maybe 2008? Of course, the Definity  
is so
easy to figure out, you hardly need a manual ... Definitely need  
them on

the Meridian though :O

Best,

Sean

Re: De-yellowing

[Chuck Guzis]

On 08/22/2015 11:04 AM, Pete Turnbull wrote:


Hydrogen peroxide *is* a bleach, as any chemist can tell you.  Never
 heard of "peroxide blonde"?


Has anyone tried ditching the peroxide and simply gone to using a 
solution of sodium percarbonate (e.g. "Oxyclean")?  Cheap and pretty 
shelf-stable in the powder form.


Not that I care about yellow plastic.  It's all going to crumble eventually.

--Chuck

Re: 9-Track 1/2" Tape Drive Recommendations?

[Chuck Guzis]

On 08/22/2015 10:07 AM, Jay Jaeger wrote:


One other type:  spring arm, where the tape reels do all the tape
moving, and a speed sensor, rather than a traditional capstan.  The
tension arm is part of the servo system to which the reel motors
respond.  In this case the reel motors and tension arm are anything
but independent.



Historically, the two are very different in application.  If you've got 
a COBOL handy on your tape system, try running the 1974 Navy Audit 
Tests, once the set of benchmarks by which CODASYL compliance of a 
vendor's COBOL was judged. (Al, do you have a copy of those on bitsavers?)


Very short tape records were written and read back in one of the tests 
(I forget which one; it's been 40 years after all).  Vacuum-column tape 
drives made the most itneresting noises as they went through their 
start-top tape motion.  You could actually play melodies on some of 
them, simply by varying the block length.


Vacuum-column drives, if you will, are inertia-trading devices. The reel 
motors are powerful in a 300 ips drive; they have to be. Practically 
speaking, it's not realistic to expect the system composed of the mass 
of the tape reels and the motors behind them to go from 0 to 300 ips in 
a fraction of a second--nor, to do it accurately.  So, the reel motors 
handle the approximate movement of the high-inertia reel system and only 
maintain a few feet of loose tape, held in the vacuum columns, said 
short length massing almost nothing.  The capstan(s) can then manage the 
quick tape movements quite nicely.  The nature of the capstan mechanism 
varied between manufacturers--some used a pinch-roller sort of affair; 
the others used perforated capstans whose selection of nothing, vacuum 
or positive pressure could be managed quite nicely by a voice-coil valve.


The point is that during the 50s and much of the 60s, diskless/drumless 
systems were not uncommon (anyone remember S/360 TOS?) and tapes were 
used as working storage.  Sometime during the 70s, with the 
proliferation of disk storage, tapes became relegated to archival or 
offline storage, not working storage.  Pick up a copy of Flores or Knuth 
on sorting and you can see how important tapes were for handling and 
manipulating large amounts of information.


Comes the minicomputer and you begin to see spring-arm and direct servo 
drive units aimed toward the archival use of tapes--that is, a tape held 
information to be copied to a disk, so start-stop on a dime wasn't 
necessary.  If one overshot a record, the drive/formatter only needed to 
bring the tape to a halt and read backwards until the gap before the 
desired block was reached, then back up another block or so and get a 
running start at the target.


This change in role probably is what governed the brain-dead treatment 
of tape by later operating systems such as UNIX and PRIMOS, to name a 
couple.  Until the advent of cheap cartridge tapes, almost all 
microcomputer OSes were utterly ignorant of the existence of tapes.


--Chuck

RE: De-yellowing

[Dave G4UGM]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Pete
> Turnbull
> Sent: 22 August 2015 19:05
> To: gene...@classiccmp.org; discuss...@classiccmp.org:On-Topic and Off-
> Topic Posts 
> Subject: Re: De-yellowing
> 
> On 22/08/2015 13:50, Tothwolf wrote:
> > On Sat, 22 Aug 2015, Dave G4UGM wrote:
> 
> >> All the techniques discussed so far involve using a "bleach" of some
> >> kind and possibly UV light. Some use other materials so you have a
> >> gell which makes it easier to apply.
> >> From what I have read yellowing usually/often/always re-occurs..
> >
> > Hydrogen Peroxide, not bleach.
> 
> Hydrogen peroxide *is* a bleach, as any chemist can tell you.  Never heard
of
> "peroxide blonde"?
> 

I should probably have said a ""peroxide based bleaching agent" as most
folks assume "bleach" means "chlorine based bleach" which is not what is
being used here.
However there are several variations on this theme and several slightly
different chemicals have been used as the bleach...

> --
> Pete
> 
> Pete Turnbull

Dave Wade

Re: De-yellowing

[Pete Turnbull]

On 22/08/2015 13:50, Tothwolf wrote:

On Sat, 22 Aug 2015, Dave G4UGM wrote:



All the techniques discussed so far involve using a "bleach" of some
kind and possibly UV light. Some use other materials so you have a
gell which makes it easier to apply.
From what I have read yellowing usually/often/always re-occurs..


Hydrogen Peroxide, not bleach.


Hydrogen peroxide *is* a bleach, as any chemist can tell you.  Never 
heard of "peroxide blonde"?


--
Pete

Pete Turnbull

Re: A tale of woe, including carelessness, stupidity and laziness....

[Tapley, Mark]

Jay,
this is a really great post. I feel really bad for you - having the 
same piece of equipment go bang/flash more than once would have been totally 
demoralizing to me - but I really admire both your tenacity and your 
willingness to share this with the rest of us. 
Thank you! Sure hope that disk is spinning its proper string of bits 
before long. You deserve the chance to post a victory story soon!

- Mark

On Aug 20, 2015, at 9:57 PM, Jay Jaeger  wrote:

> What follows is a tale of carelessness, stupidity and laziness. So far,
> I haven't found an excuse to add ignorance to the list. ;)  As you may
> recall, I was testing an 8" floppy drive that was reading inconsistently
> on an Altos 8000 system, when, while testing with a replacement drive,
> the 24V power supply gave out.
> 
> First I acquired a replacement series pass (2N3055) from Radio Shack.
> That did not seem to fix the problem.  Further, due to *carelessness*
> (#1) during the replacement and testing of the 2N3055, I managed to
> break the center lead off of the TIP31A which drives it.
> 
> So, I ordered a replacement for the TIP31A, and, while I was at it,
> ordered several LM723 Voltage Regulators, just in case (good idea, as it
> turned out).  Then, I replaced the TIP31A, put it back together and ---
> nothing. No output. Oh well, I guess the LM723 must be bad.
> 
> Then, in the process of checking that out, I tilted the board over on
> its back and, due to my *carelessness* (#2) and *stupidity* (#3))
> FLASH!!!  BANG  POP
> 
> Though switched off, the power supply was still plugged in - I had
> neglected to unplug it. The board came in contact with what SHOULD HAVE
> BEEN neutral, which likely would have caused no harm.  I didn't actually
> realize that until I was on my way back home with the parts to replace
> what had blown out.
> 
> [Also a design note:  Altos did not cover up the input terminals on the
> transformer or use quick disconnect plugs - either of which would have
> saved the day.]
> 
> After some thought (and a test), I realized that, due to prior laziness
> / neglect (#4 - about 10 years+ worth), and a dose of stupidity, the
> mains hot and neutral were reversed on my bench.  Thus the power switch
> was on the neutral side, and the mains to the power supply was "hot"
> even when not turned on.
> 
> At least this was not *originally* my fault. That circuit came that way
> when we bought the house. But, out of laziness, neglect and stupidity, I
> had not fixed it, even though I had known about it for years.
> 
> So, this blew up the -12V supply (quite literally) -- cross out a pair
> of rectifiers, an LM723 voltage regulator (spectacularly blown up, with
> a hole in middle and two leads blow away), and a 2N2905 transistor, a
> couple of resistors and a trace on the circuit board. (At the time, the
> 2N3055 series pass transistor was not connected in the circuit).  The
> fuse didn't blow - it wasn't part of the circuit, being on the neutral
> side of things because of the miss-wired mains in the house - the short
> was from hot to ground.  (A GFCI, had I had one, would undoubtedly have
> tripped).
> 
> Next, I pulled out all the blown components, and tested what was left.
> Being at least halfway clever, I proceeded to test the +24V and +12V
> supplies first.  Once I replaced the original LM723 on the +24V supply,
> which was already undoubtedly bad, the +24V supply was fine - the short
> to the mains had not affected it. But the +12V supply's LM723 had
> apparently been collateral damage - the -12V supply uses the +12V supply
> as part of its LM723 circuit, so the two are connected.  (I knew
> something was wrong, because even though I could set the supply +12V,
> the adjustment worked backwards, and under load the voltage dropped too
> much).
> 
> So, I replaced the +12V supply LM723, and the +12V supply came back to
> life. Both tested fine under load, no ripple, only 20mv of noise.
> During these tests, I moved the same 2N3055 from circuit to circuit to
> avoid having to completely reassemble the supply. That saved time.  But,
> do you think I was done being careless?   Noope.
> 
> Next, I soldered in the components for the -12V supply, including its
> 2N3055, and turned it on.  KA-BANG!!!  FLASH!!!  DEBRIS CLOUD !!!  Out
> of carelessness (#5) I had managed to put the electrolytic input
> capacitors in BACWARDS. I now had a nice coil of cardboard and aluminum
> sticking up out of one of them.  Then the next day (today) I found the
> can itself lying on the floor - this power supply predates the modern
> practice of scored break lines in electrolytic capacitors.  It could
> easily have hit me in the eye.
> 
> So, I took both of those capacitors out, and tested the one that had not
> blown up. It seemed to be OK - no excessive leakage. So, I put in a
> replacement and... 0V output.
> 
> Blown fuse. What th

Re: 9-Track 1/2" Tape Drive Recommendations?

[Jay Jaeger]

On 8/22/2015 5:32 AM, Brent Hilpert wrote:
> On 2015-Aug-21, at 10:20 PM, Ali wrote:
> 
> A brief conceptual overview:
> 
> Vacuum-column and spring-arm drives comprise 3 servo systems:
>   - each reel motor is in a closed servo loop with position sensors in 
> its associated vacuum column or spring arm.
>   - the capstan motor, driving the exposed tape between the reels, is in 
> a servo loop with a tape-speed sensor,
> and externally controlled by commands for forward/reverse and speed 
> selection.
> 
> The 3 servo systems are electrically independent (in control terms and 
> leaving aside power supplies).
> The connection between them is the tape.
> 

One other type:  spring arm, where the tape reels do all the tape
moving, and a speed sensor, rather than a traditional capstan.  The
tension arm is part of the servo system to which the reel motors
respond.  In this case the reel motors and tension arm are anything but
independent.

Example:  HP 88780

JRJ

RE: Data I/O 29B

[Jay West]

I'm confused that you couldn't find any info on these. I have a 29B with
quite a few different attachments. These are about the best documented units
I've seen. I probably have 3 or 4 inches of documentation (fairly sure it
includes schematics), and at least 3 different versions of DOS programs that
allow you to control and automate the unit. ISTR a unix one floating around
as well. I know the docs include "thousands" of pinout families referenced
to which chips they are for...

I believe I scrounged all this from google years back. Let me know if you
can't find info

J

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Billy
Pettit
Sent: Friday, August 21, 2015 7:34 PM
To: General Discussion: On-Topic and Off-Topic Posts 
Subject: Data I/O 29B

I have a small batch of Data I/O EPROM burners.  Trying to test them out and
ran into a nightmare.  They require a pin family and size parameter.  But in
none of the documentation is there any mention of what these values are.
There are some generic pinouts, which are almost useless because Data I/O
changed the definition of several pins.

Then the manual says to get your part's timing chart and compare them to 409
pages of timing charts to find the family type!  Nothing is mentioned
anywhere on how to calculate size parameter.

There should be a chart or document somewhere that gives the parameters by
model numbers like 2516, 2764, etc.

Anyone know of a document like this?

Anyone have experience with the model 29A&B, Model 19, Model 100 gang
programmer, etc.

At this point, without better data, these 11 -12 deveces are heading for the
scrap pile.  This is the poorest documentation I've ever seen on a piece of
test equipment.

Billy Pettit

Silent 785 docs?

[Jay West]

I've got a TI Silent 785 I'm trying to get configured/running. I see docs on
bitsavers for the earlier models, but not anything in the 780 series and
outwardly they do appear to be somewhat different than the 700 series. My
google searches don't return joy either. I'm particularly looking for serial
port configuration.

 

Anyone have operators and/or service manual for the Silent 785?

 

J

Re: 5.25 floppies that read but don't write

[Mike Stein]

Do we know the make/model of this drive?

- Original Message - 
From: "Marc Verdiell" 

To: 
Sent: Saturday, August 22, 2015 12:50 AM
Subject: RE: 5.25 floppies that read but don't 
write




Chuck,
I looked at the pin 2 signal and resulting drive 
behavior. It doesn't
properly auto-switch between densities as it 
should. It does switch it for
reading, but not for writing. Below is the full 
story.


There is one jumper that controls DD/HD 
switching mode.


In the auto position, I can read both HD and DD 
formats (I use the right
diskettes for either format). You can see the 
computer on pin 2 (density
select) trying both positions, settling on the 
right one (high for HD, low

for DD), and reading the disc correctly.
That's great. But when writing, although pin 2 
goes to the right level, the
floppy seems to ignore it. It will always write 
at DD, and refuse to write

in HD (no signal at the head).

Interestingly, in the fixed density position 
(should be HD only), it WILL
write at 1.2M HD! The write signal does appears 
at the head. Unfortunately
in this setting it will NOT switch the reading, 
get stuck reading only DD

and fail on HD.

So I can either have the reading HD or the 
writing HD, but not the two at
the same time. That's why a regular format 
fails. The density switching
logic seems to have a problem. Rather than track 
down which IC or transistor
failed on the board it might be much simpler to 
get another 5.25 floppy. In
the meantime my understanding of these simple 
critters has improved a lot.


Marc

At high density, have you taken a good look at 
pin 2 of the floppy
interface?  Have you checked to see if pin 2 is 
configured (via jumpers)

as "density select"?
--Chuck

Re: 9-Track 1/2" Tape Drive Recommendations?

[Jon Elson]

On 08/22/2015 12:20 AM, Ali wrote:

Jon,


Enough Pertec drives were made so that manuals should be no problem.
Some other makes were made in fairly small numbers so manuals may be a
problem.

I should have been more clear - the manuals were for the ISA interface card
and the accompanying SW not for an particular drive.
If you are buying a 30+ year-old tape drive, you WILL NEED 
the manuals!  There may be setup options that need to be 
configured, or there may be something wrong with the drive.  
Obviously, you won't be buying a new 1/2" tape drive with 
factory warranty, and these things are both complex and 
finicky, compared to typical computer hardware.



You have to decide, spring-arm, vacuum-column or streaming, and then
most dual density drives were either 800/1600 or 1600/6250.  Few would
do all three.  (Also there's 3200 BPI, identical to 1600 PE mode, just
double the clock, but it is a fairly rare setup.)

Thanks for the info. I had seen (on YouTube) videos of the vacuum-column and
streaming drives. The spring arm I am not familiar with. Is it just an arm
that produces tension on the tape keeping it in place?
yes, a cheaper version of the vacuum column.  usually used 
only on slower drives, but I have seen them up to 45 IPS.

Oh, with "Pertec interface" there are TWO FLAVORS!  The old system was
Pertec unformatted, with 3 cables.
Write, Read and Control.  Later was Pertec formatted, with two cables.
They are totally incompatible, so make sure you get drives compatible
with your interface.

Thanks again. I was not aware of this. My card has the two 50 pin edge
connectors coming from one cable that terminates in a D-Sub so I would say
this is the Pertec formatted interface. I could also go SCSI as long as the
tape drives would follow "standard" SCSI commands but those type of drives
seem even more expensive.


I've been looking for a SCSI 1/2" drive (or conversion 
boards for my CDC 92185's) for years.  Never found one.  I 
did rescue a SCSI to Pertec-formatted converter box off a 
scrap drive, and it WORKED the first time I powered it up, 
then the darn thing quit with a power on self test error!  
Arrgh!


Jon

Looking for Vintage Gold Lead LEDs for SCELBI project

[Nick Allen]

Hey everyone, I am looking for some vintage Gold-Lead clear LEDs that 
light up red for a Scelbi project I am working on for VCFMW.  Will need 
29 of them if you have them, willing to trade or buy them, thnx!!


-Nick

Re: Data I/O 29B

[John Robertson]

On 08/21/2015 5:33 PM, Billy Pettit wrote:

I have a small batch of Data I/O EPROM burners.  Trying to test them out and 
ran into a nightmare.  They require a pin family and size parameter.  But in 
none of the documentation is there any mention of what these values are.  There 
are some generic pinouts, which are almost useless because Data I/O changed the 
definition of several pins.

Then the manual says to get your part's timing chart and compare them to 409 
pages of timing charts to find the family type!  Nothing is mentioned anywhere 
on how to calculate size parameter.

There should be a chart or document somewhere that gives the parameters by 
model numbers like 2516, 2764, etc.

Anyone know of a document like this?

Anyone have experience with the model 29A&B, Model 19, Model 100 gang 
programmer, etc.

At this point, without better data, these 11 -12 deveces are heading for the 
scrap pile.  This is the poorest documentation I've ever seen on a piece of 
test equipment.

Billy Pettit


There is a good support group for these machine hosted by Alfred Morin 
on yahoo.


To join etc, :

https://groups.yahoo.com/neo/groups/Data_IO_EPROM

Also, I have a bit of Data I/O stuff filed away here (not well sorted 
I'm afraid) from TTL - Tech Tools (mail) List:


FTP site is:ftp://ttl.arcadetech.org/TTL/Test_Equipment


https://pairlist7.pair.net/mailman/listinfo/techtoolslist


John :-#)#

Re: Update on SA-800 Problem

[Jay Jaeger]

On 8/22/2015 12:20 AM, Chuck Guzis wrote:

> On 08/21/2015 06:46 PM, Jay Jaeger wrote:
> 
>> One other thing I have noticed is that sometimes after a read problem
>> on the bad drive the FD 1791 floppy controller chip seems to get into
>> a "snit" that even a reset does not cure - I have to cycle power to
>> get it back.  Now that I have a reliable drive as the first drive, it
>> is clear that this is not a reinsertion / wobble issue.  So, I will
>> have to check the reset line going to that and the PIO chip that
>> supports it to see if there is a problem on the board.  I also have
>> some spare FD 1791's I can try, that are of a slightly later
>> revision, to see if the problem is related to that specific chip.
> 
> Try a later revision of the 91.  We had miserable problems with the
> WD1781 (the FDC that no one has heard of) and eventually had to
> incorporate an external register bit into the design to enable software
> to do a "hard" reset of the 1781.  It could occasionally just go deaf
> and dumb; WDC knew about the problem and that was the only solution
> offered.
> 
> --Chuck
> 
> 

Yes, my thought as well.

Re: HP 5480A, or, obscure HP instruments / was Re: More on manuals plus rescue

[Jay Jaeger]

On 8/22/2015 8:14 AM, Tothwolf wrote:

> 
> It only helps a little though and when eBay eliminated wildcard matching
> awhile back, they also reduced the maximum query length. What I /really/
> don't like about eBay's current search system, is how it substitutes
> keywords internally. If I search for "Compaq", I don't want results for
> "HP", and likewise if I search for "HP", I don't want results for
> "Compaq"...
> 

There is a lot that eBay gets wrong.  The opportunity available to them
is enormous, but they just don't grasp it.  PayPal made making money
easy enough that eBay got left by the wayside.  Maybe now things can get
better - because if they don't they may not survive.  Posting something
directly online is tortuous, terribly confusing for newbies, and using
their "TurboLister" isn't much better.

JRJ

Re: Data I/O 29B

[wulfman]

thats it. I hardly ever use the data IO unless i need to burn a bipolar prom
i have anther prom programmer much newer that does everything except
bipolar proms

thanks rik been a while since i used it and forget the name




On 8/22/2015 6:31 AM, Rik Bos wrote:
> The software is pl.exe " promlink".
> On the dataio yahoo group you can find the link and lots of info regarding 
> data io equipment.
> I use it a lot for programming proms, like the HP 1000 boot proms.
>
> -Rik
>
> -Oorspronkelijk bericht-
> Van: "Noel Chiappa" 
> Verzonden: ‎22-‎8-‎2015 15:17
> Aan: "cctalk@classiccmp.org" 
> CC: "j...@mercury.lcs.mit.edu" 
> Onderwerp: Re: Data I/O 29B
>
> > From: wulfman
>
> > I have a modified dos program that talks to the data i/o
> > its the one that they sold with the unit but only ran on a 286
> > ...
> > the modified one i have works in windows 7 in a dos box
>
> I seem to recall that I downloaded some software to run my 29B (although I
> have yet to work with it extensively), and that it did run in a DOS box under
> Windows 98? Is that the '286' one you're referring to?
>
> If so, maybe that won't run in a DOS box under the later versions of Windows?
> Or maybe I have a different program from the one you're talking about? (Or
> maybe I somehow downloaded an already-fixed version?)
>
> > if your interested i can send it to you
>
> Other than running under Windows 7, does it have any other improvements?
> If so, I might be interested.
>
> Whatever the case, if you would like someone to host it for open download,
> let me know.
>
>   Noel
>


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RE: De-yellowing

[tony duell]

> 
> Within a museum context, where showing original factory condition is
> probably a desirable thing, have there been any studies to ensure that
> retrobright (or other treatments) don't cause any damage to the plastics
> (e.g. making the surface less resistant to scratches, or the plastic more
> brittle, say)?

As somebody who doesn't care too much about the appearance or colour
of the machines in my collection, the only reason I would try to de-yellow
something is if it prevented further deterioration of the plastic (not the 
colour,
but the fact that some plastics turn very brittle with age, for example).

I do not believe retrobrite does this (does it?) 

I don't know of a treatment that does, is there one?

> 
> Personally I quite like the patina of a yellowed machine anyway - being
> able to see how it sat in a room, or where stickers used to be and such;
> it's a minor thing, but sometimes it does tell a little bit of a story.
> Maybe in 20 years if I ever sell any of my collection I might consider it,
> but for now they may as well stay yellow :)

I'm leaving mine alone (and not just because I am lazy). It would appear you
can use retrobrite at any time, but you can't undo the effects of it. So I'll
keep my machines as they are (unless there is some treatment to 
prolong the life of the plastic), if some future owner wants to deyellow them
after I am in a pine box, they can.

-tony

Re: De-yellowing

[Tothwolf]

On Sat, 22 Aug 2015, Jules Richardson wrote:

On 08/22/2015 07:48 AM, Tothwolf wrote:

On Sat, 22 Aug 2015, Jules Richardson wrote:

On 08/21/2015 05:28 PM, Evan Koblentz wrote:


Google for "Retr0brite".


I've never tried the stuff - but is it a permanent fix, or does the 
yellowing gradually come back?


It almost always seems to comes back to some extent. De-yellowing 
treatments only work on the outermost surface of the plastic, and there 
are still plenty of free bromides just under the treated surface which 
will migrate outward. The re-yellowing (which may or may not be much 
less than the original yellowing) also occurs much faster than the 
original yellowing. Unless you can somehow eliminate all the free 
bromides from the plastic, de-yellowing treatments such as Retr0brite 
are just a temporary cosmetic fix.


I thought that might be the case, but thought I might be mistaken given 
how many people seem to rave about how wonderful this stuff is.


It does give something a nice temporary cosmetic fix, but in most cases it 
just doesn't last. As little as a year later something can be completely 
yellow again. It probably has a lot to do with the specific amount of 
bromide and other stuff in the plastic.


Within a museum context, where showing original factory condition is 
probably a desirable thing, have there been any studies to ensure that 
retrobright (or other treatments) don't cause any damage to the plastics 
(e.g. making the surface less resistant to scratches, or the plastic 
more brittle, say)?


Long term UV exposure isn't exactly good for plastics, but I can't see 
lower concentrations of Hydrogen Peroxide doing any damage. Heavy UV 
exposure tends to make a lot of thermoplastics very brittle.


Personally I quite like the patina of a yellowed machine anyway - being 
able to see how it sat in a room, or where stickers used to be and such; 
it's a minor thing, but sometimes it does tell a little bit of a story. 
Maybe in 20 years if I ever sell any of my collection I might consider 
it, but for now they may as well stay yellow :)


I had my yellowed TRS-80 Model 100 out yesterday to finally remove its 
internal NiCd battery (I caught it just in time, there was a tiny amount 
of discoloration of the solder mask at one end, which is probably the 
copper trace tarnishing, but the solder mask was still firmly adhered to 
the copper). It would be nice if the machine weren't yellowed, but the 
yellowing doesn't stop me from using it.


My model 100 has mostly lived in a box since I bought it (keeps the dust 
out of the keyboard when I'm not tinkering with it) and it has a very even 
yellowing to the light colored plastic (I don't think it has worsened any 
since I got it). I just haven't been able to justify the time and the cost 
of the materials to "retr0brite" it since I know the yellowing would 
reoccur, even with it stored in a box.


Maybe someone will eventually come up with a way to bring those free 
bromides out to the surface where the Hydrogen Peroxide will take care of 
them.


I wouldn't think it would make much of a difference, but has anyone tried 
putting a plastic part under vacuum to see if that helps?

RE: Data I/O 29B

[Rik Bos]

The software is pl.exe " promlink".
On the dataio yahoo group you can find the link and lots of info regarding data 
io equipment.
I use it a lot for programming proms, like the HP 1000 boot proms.

-Rik

-Oorspronkelijk bericht-
Van: "Noel Chiappa" 
Verzonden: ‎22-‎8-‎2015 15:17
Aan: "cctalk@classiccmp.org" 
CC: "j...@mercury.lcs.mit.edu" 
Onderwerp: Re: Data I/O 29B

> From: wulfman

> I have a modified dos program that talks to the data i/o
> its the one that they sold with the unit but only ran on a 286
> ...
> the modified one i have works in windows 7 in a dos box

I seem to recall that I downloaded some software to run my 29B (although I
have yet to work with it extensively), and that it did run in a DOS box under
Windows 98? Is that the '286' one you're referring to?

If so, maybe that won't run in a DOS box under the later versions of Windows?
Or maybe I have a different program from the one you're talking about? (Or
maybe I somehow downloaded an already-fixed version?)

> if your interested i can send it to you

Other than running under Windows 7, does it have any other improvements?
If so, I might be interested.

Whatever the case, if you would like someone to host it for open download,
let me know.

Noel

Re: Data I/O 29B

[Noel Chiappa]

> From: wulfman

> I have a modified dos program that talks to the data i/o
> its the one that they sold with the unit but only ran on a 286
> ...
> the modified one i have works in windows 7 in a dos box

I seem to recall that I downloaded some software to run my 29B (although I
have yet to work with it extensively), and that it did run in a DOS box under
Windows 98? Is that the '286' one you're referring to?

If so, maybe that won't run in a DOS box under the later versions of Windows?
Or maybe I have a different program from the one you're talking about? (Or
maybe I somehow downloaded an already-fixed version?)

> if your interested i can send it to you

Other than running under Windows 7, does it have any other improvements?
If so, I might be interested.

Whatever the case, if you would like someone to host it for open download,
let me know.

Noel

Re: HP 5480A, or, obscure HP instruments / was Re: More on manuals plus rescue

[Tothwolf]

On Thu, 20 Aug 2015, Jay Jaeger wrote:

On 8/20/2015 7:11 AM, tony duell wrote:


They reuse numbers for what I call "marketing numbers".  For example, 
with a LaserJet 8150dn, the "8150" is a "marketing number" and not the 
actual HP product number, which was C4267A.  As far as I know they've 
never actually reused a product number.


I know that's no consolation when you search for "HP 5480" for that 
product, and get printers or supplies with that "marketing number" 
instead.


I get irritated when I search for HP9100 (meaning the first desktop 
scientific calculator thing) and get hits for some modern-ish 
printer/scanner. Admittedly that is a 9100C (the calculators were 9100A 
and 9100B), but...


At least, under Google and eBay, one can add exclusionary terms:

hp 9100 -printer -scanner

Seems to do pretty well under Google.  Under eBay I had to add a lot 
more exclusions, and ran out of room.


With eBay, you can also group them: -(printer,scanner)

It only helps a little though and when eBay eliminated wildcard matching 
awhile back, they also reduced the maximum query length. What I /really/ 
don't like about eBay's current search system, is how it substitutes 
keywords internally. If I search for "Compaq", I don't want results for 
"HP", and likewise if I search for "HP", I don't want results for 
"Compaq"...

Re: De-yellowing

[Jules Richardson]

On 08/22/2015 07:48 AM, Tothwolf wrote:

On Sat, 22 Aug 2015, Jules Richardson wrote:

On 08/21/2015 05:28 PM, Evan Koblentz wrote:


So, how does one de-yellow something?  I have a VT-100 and some other
gear that could use that process.


Google for "Retr0brite".


I've never tried the stuff - but is it a permanent fix, or does the
yellowing gradually come back?


It almost always seems to comes back to some extent. De-yellowing
treatments only work on the outermost surface of the plastic, and there are
still plenty of free bromides just under the treated surface which will
migrate outward. The re-yellowing (which may or may not be much less than
the original yellowing) also occurs much faster than the original
yellowing. Unless you can somehow eliminate all the free bromides from the
plastic, de-yellowing treatments such as Retr0brite are just a temporary
cosmetic fix.


I thought that might be the case, but thought I might be mistaken given how 
many people seem to rave about how wonderful this stuff is.


Within a museum context, where showing original factory condition is 
probably a desirable thing, have there been any studies to ensure that 
retrobright (or other treatments) don't cause any damage to the plastics 
(e.g. making the surface less resistant to scratches, or the plastic more 
brittle, say)?


Personally I quite like the patina of a yellowed machine anyway - being 
able to see how it sat in a room, or where stickers used to be and such; 
it's a minor thing, but sometimes it does tell a little bit of a story. 
Maybe in 20 years if I ever sell any of my collection I might consider it, 
but for now they may as well stay yellow :)


cheers

Jules

RE: De-yellowing

[Tothwolf]

On Sat, 22 Aug 2015, Dave G4UGM wrote:

On Sat, 22 Aug 2015, Jules Richardson wrote:

On 08/21/2015 05:28 PM, Evan Koblentz wrote:

So, how does one de-yellow something?  I have a VT-100 and some other 
gear that could use that process.


Google for "Retr0brite".


I've never tried the stuff - but is it a permanent fix, or does the 
yellowing gradually come back?


All the techniques discussed so far involve using a "bleach" of some 
kind and possibly UV light. Some use other materials so you have a gell 
which makes it easier to apply.

From what I have read yellowing usually/often/always re-occurs..


Hydrogen Peroxide, not bleach.

Re: De-yellowing

[Tothwolf]

On Sat, 22 Aug 2015, Jules Richardson wrote:

On 08/21/2015 05:28 PM, Evan Koblentz wrote:

So, how does one de-yellow something?  I have a VT-100 and some other 
gear that could use that process.


Google for "Retr0brite".


I've never tried the stuff - but is it a permanent fix, or does the 
yellowing gradually come back?


It almost always seems to comes back to some extent. De-yellowing 
treatments only work on the outermost surface of the plastic, and there 
are still plenty of free bromides just under the treated surface which 
will migrate outward. The re-yellowing (which may or may not be much less 
than the original yellowing) also occurs much faster than the original 
yellowing. Unless you can somehow eliminate all the free bromides from the 
plastic, de-yellowing treatments such as Retr0brite are just a temporary 
cosmetic fix.

RE: De-yellowing

[Dave G4UGM]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Jules
> Richardson
> Sent: 22 August 2015 13:25
> To: gene...@classiccmp.org; discuss...@classiccmp.org:On-Topic and Off-
> Topic Posts 
> Subject: Re: De-yellowing
> 
> On 08/21/2015 05:28 PM, Evan Koblentz wrote:
> >
> >> So, how does one de-yellow something?  I have a VT-100 and some other
> >> gear that could use that process.
> >
> > Google for "Retr0brite".
> 
> I've never tried the stuff - but is it a permanent fix, or does the
yellowing
> gradually come back?

All the techniques discussed so far involve using a "bleach" of some kind
and possibly UV light. Some use other materials so you have a gell which
makes it easier to apply. 
>From what I have read  yellowing usually/often/always  re-occurs..

Dave

Re: De-yellowing

[Jules Richardson]

On 08/21/2015 05:28 PM, Evan Koblentz wrote:



So, how does one de-yellow something?  I have a VT-100 and some other
gear that could use that process.


Google for "Retr0brite".


I've never tried the stuff - but is it a permanent fix, or does the 
yellowing gradually come back?

(OT?) Copyright and IP

[Alexis Kotlowy]

Hi List,

This relates to the ongoing discussion about vintage computer software
copyright.

A year or so ago I did some Beta videotape backups for the Australian
Computer Society. They're of keynote speeches at the 10th Australian
Computer Conference in 1983. One that I'd like to mention is by Tania
Amochev from (then) Control Data Corporation, titled Information
Services of the Future.

In it, things we now call data mining and Google AdSense are discussed,
and the potential of data services in general (this is in 1983). One
thing that struck me was the contrast between traditional copyright of
material items, and how such ideas don't apply very well to non-material
information.

I was left with the impression that the idea of "Intellectual Property"
is in some ways an attempt to force information to be treated like
materials, which is an easy way to put a value information, but also
allows it to be hoarded. This goes directly against how information
behaves, which is to flow freely. This free-flow of information allows
more information to be derived or generated, enhancing productivity and
overall knowledge.

To quote: "Information is diffusive - it leaks. The more it leaks, the
more of it there is. Information is aggressive, even imperialistic. It
simply breaks out of its unnatural bonds, the bonds of secrecy in which
'thing minded' people try to lock it. So secrecy, property rights,
confidentiality, all enshrined in Western thought and law, are not
particularly effective restraints on information."

This is not a cry to abolish copyright and intellectual property laws,
but to highlight some of the inadequacies of the thought process behind
these laws when dealing with high speed, global information.

Does anyone have any thoughts? If there was a massive shift in the
fundamental philosophy of how information should be valued, where would
you like that shift to go? For example, is there a way to pay
programmers and similar professions by the quality of their work, rather
than just the number of lines of code they write. How do you measure the
quality of information?

I'll see if I can get permission to have the six keynote addresses put
online, because they're all fascinating.

Cheers,

Alexis.

P.S., if this is way off topic, my apologies.

Re: 9-Track 1/2" Tape Drive Recommendations?

[Brent Hilpert]

On 2015-Aug-21, at 10:20 PM, Ali wrote:
> Jon,
> ...
>> You have to decide, spring-arm, vacuum-column or streaming, and then
>> most dual density drives were either 800/1600 or 1600/6250.  Few would
>> do all three.  (Also there's 3200 BPI, identical to 1600 PE mode, just
>> double the clock, but it is a fairly rare setup.)
> 
> Thanks for the info. I had seen (on YouTube) videos of the vacuum-column and
> streaming drives. The spring arm I am not familiar with. Is it just an arm
> that produces tension on the tape keeping it in place?

A brief conceptual overview:

Vacuum-column and spring-arm drives comprise 3 servo systems:
- each reel motor is in a closed servo loop with position sensors in 
its associated vacuum column or spring arm.
- the capstan motor, driving the exposed tape between the reels, is in 
a servo loop with a tape-speed sensor,
  and externally controlled by commands for forward/reverse and speed 
selection.

The 3 servo systems are electrically independent (in control terms and leaving 
aside power supplies).
The connection between them is the tape.

The vacuum-columns or spring-arms serve to implement a length of 'buffer' tape 
between each reel and the heads and capstan.
The point of the buffer area is it is a very small mass of tape so movement of 
the tape over the heads can be started and stopped (by the capstan) very 
quickly. That is, it mechanically isolates the tape movement over the heads 
from the large mass of tape in the reels.

Each reel servo acts on its own to simply try to keep the tape in the middle of 
its vacuum-column or its spring-arm in the center of swing.
(It can be fun to play with the tape or arms while the drive is at idle and see 
how the reel motors respond, although one has to be cautious and delicate about 
doing so as the reel motors pack quite a whallop; and do so with a dud tape, 
not something that matters.)

When the capstan receives a command signal and starts moving, the tape in 
between the buffer areas starts moving.
The capstan speed servo acts to maintain constant linear tape speed over the 
heads.
The moving tape upsets both vac-cols or spring-arms in the buffer areas in 
opposite directions, the reel servos now act to correct this upset.

For example, when forward motion is called for, the capstan pulls tape out of 
the supply-side buffer (out of the vac-col or pulling the spring-arm tighter).
The sensors in the supply vac-col or spring-arm direct the supply-reel motor to 
rotate to supply more tape into the buffer area.
At the same time of course, tape is sent into the take-up buffer (into the 
vac-col or releasing tension on the spring-arm) and the take-up sensors and 
reel motor respond to rotate the take-up reel to pick up tape out of the buffer 
area.

Pardon the elaboration, I just find it a very elegant design. When you see 
these drives in full-blown action, without knowing, you might think the control 
system to achieve what they do must be horribly complex, but with the 3 
independent servo loops acting in coordination it's actually quite simple.

(We'll leave auto-loading out of the discussion).

9-Track 1/2" Tape Drive Recommendations?

[Ali Fahimi]

Hello All,

Recently I came across a complete Pertec interface (card, manual, software,
and, cables) thanks to list-member Shaun. Of course what is the point of
having an interface if you have nothing to interface it to! 

So I've been looking at, and learning a bit, about 1/2" tape drives. I've
also looked into acquiring one. But before going down this path I wanted to
see what pitfalls, warning signs, etc. I should be on the lookout for. I am
looking for a unit mostly to experience the tech and to play around with. I
do not plan on recovering data from any particular system or format.
However, it would be nice if I could setup a system that actually worked for
backups of say an IBM AT for demonstration purposes.

Having read some old InfoWorld and PC Mag articles I can see there were a
number of tape drive manufacturers well into the early 90s. Based on the
reviews the Cipher and Qualstar units seem to be well suited for my
purposes. Any other brand/models I should keep an eye out for. I know IBM
also had some 1/2" 9 track tape drives (9437 and 9438) but neither was a
Pertec interface from what I have gleaned. The 9347 used a proprietary
interface and the 9348 used HVD SCSI which is atypical. There was apparently
a 9348-012 model which used narrow SCSI so should interface with a standard
Adaptec card. However, I have not been able to determine if it used standard
SCSI commands and could be accessed say with a tape backup program under
Windows 9x/NT or DOS.

Of course the biggest problem is finding one locally in the LA area.
Unfortunately my only resource is eBay and prices there are definitely not
hobbyist friendly (not to mention shipping). If anyone has a line on a
working drive in the LA area (to save on S&H and avoid the dangers of
shipping) or a reasonably priced one elsewhere I'd appreciate it. TIA for
any help.

Re: maybe OT: Powerbook 5300 OS upgrade

[Sean Caron]

Joe, that's a good offer, you should take it :O

Best,

Sean


On Fri, Aug 21, 2015 at 2:45 PM, Brent Hilpert  wrote:

> Yesterday I sent a power book 5300 to recycling.
> The display hinge was quite broken, it was given to me a while ago and I
> didn't see accomplishing anything with it.
>
> What's still kicking around here is:
> - the funky special HDI30-to-SCSI-DB25 adapter to get from the
> 5300 to normal SCSI
> - SCSI DB-25 to SCSI 50 cable
> - SCSI CDROM drive in case w power supply
>
> Also still have:
> - the 5300 power adapter/charger:  Model No. M3037(APS-76)
>
> I think the following also came with it (pile of stuff came jumbled
> together):
>
> - Global Village/teleport 56 fax/modem model A8245 (mini-DIN-8
> connector)
>
> - PowerPrint adapter: mini-DIN-8 to Centronics parallel
> - PowerPrint software on floppies
>
> - MS office and MS word on about 30 floppies
>
> Might be some other software as well.
>
> Any or all is free for shipping if you like.
> Location is Vancouver BC Canada.
> Might be able to ship from the Washington border if you're patient.
>
> I plugged the bare CD-ROM drive in (i.e. no SCSI bus connection).
> Powers up, door opens and closes, LED flashes, spins with a random disk
> inserted but doesn't seem to come ready - not sure what one would expect
> with no host on the bus.
>
>
>
> On 2015-Aug-21, at 8:30 AM, Joe Giliberti wrote:
>
> > I guess I'll be trolling ebay for a bit for a drive. Thanks Guys!
> >
> > On Fri, Aug 21, 2015 at 10:59 AM, Zane H. Healy 
> wrote:
> >
> >>
> >>> On Aug 21, 2015, at 7:45 AM, Joe Giliberti 
> wrote:
> >>>
> >>> Greetings!
> >>>
> >>> I know that many of my posts to this list tend to be on the fringes of
> >> what
> >>> is normally discussed here. I apologize in advance if this is too new
> for
> >>> the group.
> >>>
> >>> I am trying to get my Powerbook 5300 up and running as a usable word
> >>> processor (with portable printer) for school and for email. It is
> >> currently
> >>> running System 7.5.2. The machine is capable of supporting MacOS 9.1,
> but
> >>> my goal is 8.6. I see them talking on lowendmac that upgrading the OS
> >> makes
> >>> the machine more solid, but it doesn't explain how to do it. The
> machine
> >>> only has a floppy drive and no networking. Were there any system 8.6
> >>> install floppies? I can't think of another way to get it on there.
> >>>
> >>> TIA
> >>> Joe
> >>
> >> If I remember right your limited to CD.  Even on my 520c, I was able to
> >> attach an external SCSI CD-ROM drive.  It was pretty much a requirement.
> >> I'd say, definitely get it onto 8.x.
> >>
> >> I'm not sure how this is on the fringes for the list, as the system is
> >> nearly 20 years old.
> >>
> >> Zane
> >>
> >>
> >>
>
>

Re: More on manuals plus rescue

[Sean Caron]

In these times where income inequality in the USA is the worst it's been
since the Gilded Age, I think a little bit of perspective is best used when
dropping the term "meager income". If you've got pocket money for computer
collecting, I don't think you get to make that claim.

Best,

Sean



On Fri, Aug 21, 2015 at 3:36 PM, geneb  wrote:

> On Fri, 21 Aug 2015, Evan Koblentz wrote:
>
>
>> That's why I speak out against attempts to paint copyright violation as
>>> other things, such as theft: it's an appeal to emotions, trying to equate
>>> "thing I want people to oppose" with "very different thing I expect people
>>> already consider bad".  It's a fundamentally dishonest bit of oratory.
>>>
>>
>> I write for a (meager) living. If someone were to take my work and decide
>> for themselves that it should be online for free, then they ARE stealing
>> from me. That is reality, not the semantics of case law.
>>
>
> No, they're not stealing from you.  Quit taking talking points from the
> RIAA.
>
>
> g.
>
> --
> Proud owner of F-15C 80-0007
> http://www.f15sim.com - The only one of its kind.
> http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
> Some people collect things for a hobby.  Geeks collect hobbies.
>
> ScarletDME - The red hot Data Management Environment
> A Multi-Value database for the masses, not the classes.
> http://scarlet.deltasoft.com - Get it _today_!
>

Re: More on manuals plus rescue

[Sean Caron]

Perhaps, but the eBay vendor also stole the manual from HP in the first
place, as well as the profit generated in selling the copy. I don't think
they have  a lot of moral high ground ...

Best,

Sean


On Fri, Aug 21, 2015 at 10:57 AM, Evan Koblentz  wrote:

>
> Years ago I needed a HP service manual for a plotter I was trying to
>> repair that I owned. HP of course wouldn't let me have it, so I had to buy
>> a PDF copy from someone on eBay. I ended up removing the password and
>> posting it on my website.
>>
>
> That's called "stealing".
>
> The more of it turned free, the better.
>>
>
> True, but you can't just take the law into your own hands.
>

Re: More on manuals plus rescue

[Sean Caron]

That's odd, as long as I can remember, Lucent/Avaya distributed the manuals
at least for their PBX and key products pretty openly; Nortel tried to keep
them more closely held but eventually relented, too. Carrier-grade stuff
(i.e. 5ESS and SL-100/DMS-100) was always another story, of course. I don't
recall ever having any issues getting needed documentation when bringing my
Definity up and that was circa maybe 2008? Of course, the Definity is so
easy to figure out, you hardly need a manual ... Definitely need them on
the Meridian though :O

Best,

Sean


On Fri, Aug 21, 2015 at 11:50 AM,  wrote:

> In this specific case though, as it's an HP manual, if it's one of the ones
>> that went with Agilent (now Keysight) then they seem to have an
>> enlightened
>> attitude and make their old manuals available and also point to a whole
>> bunch of other places that do the same. So they may well be OK with
>> someone
>> making a manual available ... although I don't see any explicit evidence
>> that they'd be OK with someone *selling* a PDF of one of their historic
>> manuals.
>>
>
> This was a HP plotter at the end of it's service life (not a current
> model), and this entire thing happened some 12 years ago :-) But the file
> might still be on my broken home page... hmmm
>
> Hah, yep:
> https://users.757.org/~ethan/me_bookshelf/
>
> Looks like my notes on it were HP said it's discontinued and wouldn't talk
> about the machine at all. Zero. Zilch. 650C was the model.
>
> I also posted on the same web page all of the Lucent Legend manuals. At
> the time Lucent had them all available for download for free from their
> ELMO system, but it wasn't picked up by google or the like. BUT, there was
> a lot of people charging $100-$200 for the pdf files that they downloaded
> from ELMO, telling people it wasn't freely available and for purchase only.
>
> The only one who gets use of the manuals is someone who owns the hardware,
> and the hardware comes with the manuals. *Shrug*
>
>
>

Re: maybe OT: Powerbook 5300 OS upgrade

[Sean Caron]

Sorry, let me be more clear; if the machine already boots, you might be
able to mount the installation CD-ROM using an Appletalk share over
Localtalk. You can't actually net-boot the Powerbook from the Localtalk
network.

Best,

Sean


On Fri, Aug 21, 2015 at 10:55 AM, Sean Caron  wrote:

> Hi Joe,
>
> System 8 and subsequent were only available on CD-ROM. I think newest you
> can get on floppies is 7.5.3 or 7.5.5. You should be able to do the
> installation no problem with an external [Apple] SCSI CD-ROM. Might also
> work from a Localtalk share, if you have another Mac available? I don't
> know if I've ever tried that.
>
> Best,
>
> Sean
>
>
> On Fri, Aug 21, 2015 at 10:45 AM, Joe Giliberti 
> wrote:
>
>> Greetings!
>>
>> I know that many of my posts to this list tend to be on the fringes of
>> what
>> is normally discussed here. I apologize in advance if this is too new for
>> the group.
>>
>> I am trying to get my Powerbook 5300 up and running as a usable word
>> processor (with portable printer) for school and for email. It is
>> currently
>> running System 7.5.2. The machine is capable of supporting MacOS 9.1, but
>> my goal is 8.6. I see them talking on lowendmac that upgrading the OS
>> makes
>> the machine more solid, but it doesn't explain how to do it. The machine
>> only has a floppy drive and no networking. Were there any system 8.6
>> install floppies? I can't think of another way to get it on there.
>>
>> TIA
>> Joe
>>
>
>