Re: Why do good floppy disks go bad?

[Chuck Guzis]

This from Fuji may also help a bit when examining the makeup of a floppy
disk:

http://www.fujifilmusa.com/shared/bin/Magnetic_Media_Terminology.pdf

--Chuck

Re: Why do good floppy disks go bad?

[Chuck Guzis]

On 04/07/2016 10:06 PM, Tom Gardner wrote:

> And it's not likely the binder, fully cured epoxies are also very
> stable. Note disks do not have the tension problem that tape has.

There, I have to respectfully disagree.  Floppy disks do not use an
epoxy binder, but usually a polyurethane-based one. (Most are
proprietary formulations).  Hard disk coatings usually use an
epoxy-phenolic binder, but they're not on a flexible substrate.

Polyurethane isn't forever and tends to be somewhat hygroscopic.

--Chuck

Re: Data General Nova Star Trek

[Erik Baigar]

Hi Jim,

short version: Yes, I can confirm existence of such a software and
   I'd be highly interested in a copy. Of course I can
   offer digitizing it ;-)

longer version: I am preserving various Rolm (later Loral) 16 bit
machines which are hardened, military machines widely comaptible
to the DG hardware (1602 compatible to Nova and MSE14/Micro is the
hardened Eclipse). If interested, have a look at my logbook...

   http://www.baigar.de/TornadoComputerUnit/TimeLine.html#HDDsim

...datecodes 10/20/2014 to 12/15/2014 and 2/3/2015 to 2/28/2015.
Together with two friends (both maintaining a 1602B and native
DG hardware) we built a harddisc simulator to run advanced
software (e.g. RDOS). During my efforts I rescued some paper tapes
from Rolm (diagnostics)...

   http://www.baigar.de/TornadoComputerUnit/EB-RolmTapes.jpg

...and among these serious, mighty tapes was one labeled
"Star Trek 1/2". I digitized it, but without the second part
it is of nut much use, so I am sure that such a game existed
for DG hardware. From the first tape I can tell, that it is
not just the BASIC listing, but native machine code and there
is a copyright message dating 1969-1973 ;-)

The tape pile is fanfold about 10" across in a DG box specially made for such 
use.


On some occasions I had trouble reading the 30+ years old
oiled black tapes due to some holes on the folds being
obscured at the from debris of the ageing paper...

The very best from Germany,

   Erik.

RE: Why do good floppy disks go bad?

[Tom Gardner]

As a number of folks have pointed out it's not the magnetic particles - rust
is pretty stable; they read a 60 year old RAMAC at the CHM every week or so.

And it's not likely the binder, fully cured epoxies are also very stable.
Note disks do not have the tension problem that tape has.

And it's not likely the substrate, again Mylar is very stable

My guess it is both contamination and wear of the head.  After all, this is
contact recording.

Tom

Re: ADM 3a with no horizontal scan

[Seth Morabito]

* On Thu, Apr 07, 2016 at 11:34:52PM -0500, Eric Christopherson 
 wrote:
> 
> Is this the same one that was showing all exclamation points on every
> other line?

Nope, this is a different one. I got this one "as-is" in a known non-working 
state.

-Seth

Re: Space Travel (was Re: Data General Nova Star Trek)

[Pontus Pihlgren]

On Thu, Apr 07, 2016 at 04:08:42PM -0700, Charles Anthony wrote:
> 
> I have some code that does an X-11 emulation of the Atari Tempest vector
> graphics display; I'm thinking of wedging it into the simh PDP8 code to
> emulate the 338 and PDP-1 displays.
> 

That woyld be fun :) I could perhaps be used for future PDP-12 
and LINC emulators as well.

I have read just a little about the 338. I believe it is more or 
less a dedicated PDP-8. Can you say how it compares with other 
vector displas, such as VC8E?

Thanks,
Pontus

Re: ADM 3a with no horizontal scan

[Eric Christopherson]

On Thu, Apr 07, 2016, Seth Morabito wrote:
> 
> Hey folks,
> 
> I've been on a tear trying to resurrect old projects here, and next on
> the list is an ADM 3a.
> 
> This particular 3a has no horizontal scan. None at all. I just get a
> vertical line down the center of the screen. First thing I checked was
> the horizontal deflector on the yoke, which seems secure.
> 
> Before I go diving into the schematics, I figured I'd ask here: Is
> this a common failure mode? Has anyone else experienced no horizontal
> scan on a 3a? Any tips on where to look first?

Is this the same one that was showing all exclamation points on every
other line?

-- 
Eric Christopherson

Re: Pinging Joe Rigdon

[Zane Healy]

> On Apr 7, 2016, at 7:08 PM, Connor Krukosky  wrote:
> 
> Anyone know if Joe Rigdon is still around?
> 
> Thanks,
> -Connor K
> 


There is a name I haven’t heard in a *LONG* time.

Zane

ADM 3a with no horizontal scan

[Seth Morabito]

Hey folks,

I've been on a tear trying to resurrect old projects here, and next on
the list is an ADM 3a.

This particular 3a has no horizontal scan. None at all. I just get a
vertical line down the center of the screen. First thing I checked was
the horizontal deflector on the yoke, which seems secure.

Before I go diving into the schematics, I figured I'd ask here: Is
this a common failure mode? Has anyone else experienced no horizontal
scan on a 3a? Any tips on where to look first?

-Seth
-- 
Seth Morabito
s...@loomcom.com

Pinging Joe Rigdon

[Connor Krukosky]

Anyone know if Joe Rigdon is still around?

Thanks,
-Connor K

Re: Why do good floppy disks go bad?

[b...@tds.net]

You probably can't get the water heater replacement until the old COMPLETELY 
fails, which means it leaks and floods your house.

- Original Message -
From: Chuck Guzis 
To: General Discussion: On-Topic and Off-Topic Posts 
Sent: Thu, 07 Apr 2016 13:11:14 -0400 (EDT)
Subject: Re: Why do good floppy disks go bad?

On 04/07/2016 02:32 AM, Tor Arntsen wrote:
> The problem with lifetime warranties is that they're not about the 
> lifetime of the owner, and they're not about the lifetime of the 
> product. What it means is "as long as it's a product we're still 
> selling" (except for those cases where it *really* is the lifetime
> of the product.. in which case it means "the warranty is valid until
> the product fails").


Sometimes, very rarely, it does happen the other way.  The guys at the
local auto parts store tell me about the woman who comes in about every
5 years to have her car battery replaced, free of charge, since she
bought into a promotional deal for replacement batteries "for as long as
you own your car".  IIRC, she owns a 1984 Volvo.

Magazines used to offer "lifetime subscriptions", but I haven't seen
those lately.

I'm a life member of a couple of professional organizations, but I don't
know if they even exist any longer.

My water heater supposedly has a guarantee for replacement for as long
as I own my home.  I haven't had to claim a replacement yet.

--Chuck

Re: Voltage regulator with alternate voltage source...

[drlegendre .]

"...if you leave the unregulated rail _unattached_ and put +5
switcher straight onto the regulated +5 rail..."

My error, I read that as "attached".

In any event, just lift both the 7805 IN and OUT pins, and then supply
known-solid +5DC between the OUT and GND pads on the board.

No, you can't feed the IN pin with +5V, for as others have mentioned,
the 7805 has a minimum dropout of 2V or so.

On Thu, Apr 7, 2016 at 4:03 PM, William Donzelli 
wrote:

> Per his description, the 7805's input will be open. It will not try to
> source any current, as it will have none to give.
>
> I suppose there might be a little leakage.
>
> --
> Will
>
> On Thu, Apr 7, 2016 at 4:58 PM, drlegendre .  wrote:
> > Err.. unless the voltage of the switcher is identical to that of the
> 7805,
> > then one device will source current, and the other will sink it.
> >
> > Like putting two 6V batteries in parallel, where one is fresh and the
> other
> > weak. Current will flow until the potentials are equalized. But with two
> > regulated circuits, I don't see how equality can be achieved.
> >
> > Not saying it's going to smoke-out, but it does seem like a wonky thing
> to
> > do.
> >
> > On Thu, Apr 7, 2016 at 3:41 PM, wulfman  wrote:
> >
> >> You should be just fine.
> >>
> >> On 4/7/2016 1:38 PM, Bill Sudbrink wrote:
> >> > If you have a circuit which is normally designed to
> >> > operate with an unregulated supply, through a regulator...
> >> > say unregulated +8 through a 7805 to a regulated +5 and
> >> > you want to test it independent of the +8 supply, if
> >> > you leave the unregulated rail unattached and put +5
> >> > switcher straight onto the regulated +5 rail, will you
> >> > damage the 7805?  Clearly the VIN is open, but the ground
> >> > pin will still be attached.  Would this push voltage
> >> > back through and screw things up?
> >> >
> >> > Thanks,
> >> > Bill S.
> >> >
> >> >
> >> >
> >>
> >>
> >> --
> >> The contents of this e-mail and any attachments are intended solely for
> >> the use of the named
> >> addressee(s) and may contain confidential and/or privileged information.
> >> Any unauthorized use,
> >> copying, disclosure, or distribution of the contents of this e-mail is
> >> strictly prohibited by
> >> the sender and may be unlawful. If you are not the intended recipient,
> >> please notify the sender
> >> immediately and delete this e-mail.
> >>
> >>
>

Re: Why do good floppy disks go bad?

[Chuck Guzis]

On 04/07/2016 04:41 PM, Al Kossow wrote:
> 
> 
> On 4/7/16 10:11 AM, Chuck Guzis wrote: as a guarantee for replacement
> for as long
>> as I own my home.  I haven't had to claim a replacement yet.
>> 
> 
> How often do you change the anode rod?

No anode rod.  The tank is polybutylene.

I suspect that the heating element isn't part of the deal and that if it
goes, it's on my nickel.

--Chuck

Re: Why do good floppy disks go bad?

[Al Kossow]

On 4/7/16 10:11 AM, Chuck Guzis wrote:
as a guarantee for replacement for as long
> as I own my home.  I haven't had to claim a replacement yet.
>

How often do you change the anode rod?

Re: Voltage regulator with alternate voltage source...

[William Donzelli]

Does this warning assume that there is something on Vin, and not open?
With a quick look at the internal schematic of an old-school 7805, it
seems like what Bill suggests (leaving Vin open) will not actually do
much.

--
Will

On Thu, Apr 7, 2016 at 7:23 PM, John Robertson  wrote:
> On 04/07/2016 2:18 PM, Bill Sudbrink wrote:
>>
>> drlegendre wrote:
>>>
>>> Not saying it's going to smoke-out, but it does
>>> seem like a wonky thing to do.
>>
>> I disagree about "wonky" let me try with more
>> diagram and less English:
>>
>>(+8)
>>  |
>>   VIN|ceramic cap
>>  |-][-
>>   ___|   |
>>   | 7805 |--GROUND
>>      |
>>  |   |
>> VOUT|(+5)   |
>>  |   |
>>   ___|   |
>>   | LOAD |---|
>>   
>>
>> +8 is not currently available (no pun intended).
>> I would like to test LOAD without removing 7805
>> as it is soldered in place.  Is damage to 7805
>> likely if alternative regulated current is applied
>> at (+5) and (+8) is left open?
>>
>> Bill S.
>>
>>
>>
> Yes, you can damage the 7805 - READ the data sheets...
>
> Raising the Output Voltage above the Input Voltage:
>
> Since the output of the device does not sink current, forcing
>
> LM340/LM78MXX Series 3-Terminal Positive Regulators LM340/LM78MXX Series
> 3-Terminal Positive Regulators
>
> the output high can cause damage to internal low current paths in a manner
> similar to that just described in the “Short- ing the Regulator Input”
> section.
>
>
> LM340/LM78MXX Series 3-Terminal Positive Regulato John :-#(#
>
> --
> John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
> Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
>  www.flippers.com
> "Old pinballers never die, they just flip out"
>

Re: Why do good floppy disks go bad?

[Jules Richardson]

On 04/07/2016 12:11 PM, Chuck Guzis wrote:

My water heater supposedly has a guarantee for replacement for as long
as I own my home.  I haven't had to claim a replacement yet.


I wonder if that also covers parts - e.g. elements and thermostats - or if 
they try and weasel out of it and only allow a claim when something which 
really does require outright replacement happens?

Mac SE/30 analogue board and PS caps

[David Griffith]

Does anyone have a list of the capacitors on the analogue board and power 
supply for a Mac SE/30?


--
David Griffith
d...@661.org

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

Re: Why do good floppy disks go bad?

[Jules Richardson]

On 04/07/2016 12:12 PM, Chuck Guzis wrote:

I'll go one step further and state that if you hear your drive
squealing, throw the disk away and clean the heads before you insert
another disk.


If you even get the opportunity. I remember a disk - it was either Parrot 
or Wabash, I loathe them in equal measure as they seem particularly prone 
to binder problems - once squeaking in a drive, immediately followed by a 
crunch as one of the drive heads parted company with the surrounding 
structure. The heads had only just been cleaned, so all it took was the 
single read attempt to destroy the drive.


Thankfully it's only happened to me the once, but it was annoying as it was 
in a vintage machine with dual drives, which means at some point I need to 
find a matching replacement (or replace the junk + good drive with a 
matched pair)


cheers

Jules

Re: Voltage regulator with alternate voltage source...

[John Robertson]

On 04/07/2016 2:18 PM, Bill Sudbrink wrote:

drlegendre wrote:

Not saying it's going to smoke-out, but it does
seem like a wonky thing to do.

I disagree about "wonky" let me try with more
diagram and less English:

   (+8)
 |
  VIN|ceramic cap
 |-][-
  ___|   |
  | 7805 |--GROUND
     |
 |   |
VOUT|(+5)   |
 |   |
  ___|   |
  | LOAD |---|
  

+8 is not currently available (no pun intended).
I would like to test LOAD without removing 7805
as it is soldered in place.  Is damage to 7805
likely if alternative regulated current is applied
at (+5) and (+8) is left open?

Bill S.




Yes, you can damage the 7805 - READ the data sheets...

Raising the Output Voltage above the Input Voltage:

Since the output of the device does not sink current, forcing

LM340/LM78MXX Series 3-Terminal Positive Regulators LM340/LM78MXX Series 
3-Terminal Positive Regulators


the output high can cause damage to internal low current paths in a 
manner similar to that just described in the “Short- ing the Regulator 
Input” section.



LM340/LM78MXX Series 3-Terminal Positive Regulato John :-#(#

--
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
 www.flippers.com
"Old pinballers never die, they just flip out"

Re: Voltage regulator with alternate voltage source...

[John Robertson]

On 04/07/2016 2:25 PM, geneb wrote:

On Thu, 7 Apr 2016, Bill Sudbrink wrote:


Maybe I'm overthinking this.  If I just put
regulated +5 on the 7805 VIN will it work?


Isn't the minimum input voltage for a 7805, 6vdc?

g.

More like 7VDC input minimum (dropout voltage) for 7805 - there are data 
sheets you know (comment directed at Original Poster).


If the OP wants to put 5VDC in, why not cut out the 7805?

John :-#)#

--
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
 www.flippers.com
"Old pinballers never die, they just flip out"

Re: Space Travel (was Re: Data General Nova Star Trek)

[Charles Anthony]

On Thu, Apr 7, 2016 at 9:51 AM, Swift Griggs  wrote:

> On Thu, 7 Apr 2016, Pete Lancashire wrote:
> > Star Trek was a quite common BASIC (game ?) program on at least the HP
> 2000
> > time share systems, I've seen quite a few variations, on ran on RT-11.
>
> That reminds me of the "Space Travel" game/sim that Ken Thompson wrote for
> the first copy/iteration of Unix.
>
> Did anyone ever actually run/see that? There are some screenshots online
> but
> I'm curious how the original Unix on that old PDP was hitting a
> framebuffer.
> I'm really curious to know how Ken & Dennis approched it, and how far off
> from today's crazy graphics interfaces was it.
>
>
I was just looking at that graphics system; Multics had a monitor system
called XRAY that could see into memory and display live data on a PDP-8
with a 338 display. Looking at the space war source, it seems that it used
an earlier iteration of the 338, but with the same basic architecture. It
was a vector graphics display, the controller reading a command list from
memory consisting on X/Y/intensity values being fed to ADCs connected an
oscilloscope or monitor.

I have some code that does an X-11 emulation of the Atari Tempest vector
graphics display; I'm thinking of wedging it into the simh PDP8 code to
emulate the 338 and PDP-1 displays.

DECUS has PDP-8 software that runs on the 338, and the spacewar source is
available, so that should be emulatable as well.

-- Charles

Space Travel (was Re: Data General Nova Star Trek)

[Swift Griggs]

On Thu, 7 Apr 2016, Pete Lancashire wrote:
> Star Trek was a quite common BASIC (game ?) program on at least the HP 2000
> time share systems, I've seen quite a few variations, on ran on RT-11.

That reminds me of the "Space Travel" game/sim that Ken Thompson wrote for
the first copy/iteration of Unix. 

Did anyone ever actually run/see that? There are some screenshots online but
I'm curious how the original Unix on that old PDP was hitting a framebuffer.
I'm really curious to know how Ken & Dennis approched it, and how far off
from today's crazy graphics interfaces was it. 

-Swift

Re: Data General Nova Star Trek

[Pete Lancashire]

Star Trek was a quite common BASIC (game ?) program on at least the HP 2000
time share systems, I've seen quite a few variations, on ran on RT-11.

Be quite careful with the tape, the folds can be quite fragile depending on
how and where the tape was stored.

When I had my 'computer room' set up (its now put away for a major house
remodel) I had an optical reader that I modified so I could vary the read
speed down to pretty much zero CPS just for this reason.

-pete

On Thu, Apr 7, 2016 at 1:07 PM, jwsmobile  wrote:

> A friend has a large set of paper tape which seems to be from a DG User
> group (not sure about that, but label on box sort of implies that).
>
> The tape pile is fanfold about 10" across in a DG box specially made for
> such use.
>
> We hope to have a reader to digitize it soon, but wonder if anyone knows
> of such a program?  We just have the labels which say that is what the tape
> has to go on.
>
> More photos and the like later.  I know that more info would be helpful,
> but figured I'd ask first.
> thanks
> Jim
>
>

Re: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

[Lawrence Wilkinson]

On 07/04/16 00:56, Anke Stüber wrote:

the 17th edition of VCF Europe[0] is coming soon! It will take place on
April 30th and May 1st in Munich, Germany. Please be aware that the
information on the English version of the website might be outdated or
less detailed than on the German page, but Google Translate will help.


Train and hotel booked for VCFe - see you all there!

Thinking about VCFb...

--
Lawrence Wilkinson lawre...@ljw.me.uk
Ph +41(0)79 926 1036 http://www.ljw.me.uk

RE: Voltage regulator with alternate voltage source...

[geneb]

On Thu, 7 Apr 2016, Bill Sudbrink wrote:


Maybe I'm overthinking this.  If I just put
regulated +5 on the 7805 VIN will it work?


Isn't the minimum input voltage for a 7805, 6vdc?

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: Voltage regulator with alternate voltage source...

[Bill Sudbrink]

Maybe I'm overthinking this.  If I just put
regulated +5 on the 7805 VIN will it work?

Bill S.

RE: Voltage regulator with alternate voltage source...

[Bill Sudbrink]

drlegendre wrote:
> Not saying it's going to smoke-out, but it does
> seem like a wonky thing to do.

I disagree about "wonky" let me try with more
diagram and less English:

  (+8)
|
 VIN|ceramic cap
|-][-
 ___|   |
 | 7805 |--GROUND
    |
|   |
VOUT|(+5)   |
|   |
 ___|   |
 | LOAD |---|
 

+8 is not currently available (no pun intended).
I would like to test LOAD without removing 7805
as it is soldered in place.  Is damage to 7805
likely if alternative regulated current is applied
at (+5) and (+8) is left open?

Bill S.

Re: Voltage regulator with alternate voltage source...

[John Robertson]

On 04/07/2016 2:03 PM, William Donzelli wrote:

Per his description, the 7805's input will be open. It will not try to
source any current, as it will have none to give.

I suppose there might be a little leakage.

--
Will


If his intention is to bypass the 7805 then it should have both input 
and output legs cut and lifted.


John :-#)#

On Thu, Apr 7, 2016 at 4:58 PM, drlegendre .  wrote:

Err.. unless the voltage of the switcher is identical to that of the 7805,
then one device will source current, and the other will sink it.

Like putting two 6V batteries in parallel, where one is fresh and the other
weak. Current will flow until the potentials are equalized. But with two
regulated circuits, I don't see how equality can be achieved.

Not saying it's going to smoke-out, but it does seem like a wonky thing to
do.

On Thu, Apr 7, 2016 at 3:41 PM, wulfman  wrote:


You should be just fine.

On 4/7/2016 1:38 PM, Bill Sudbrink wrote:

If you have a circuit which is normally designed to
operate with an unregulated supply, through a regulator...
say unregulated +8 through a 7805 to a regulated +5 and
you want to test it independent of the +8 supply, if
you leave the unregulated rail unattached and put +5
switcher straight onto the regulated +5 rail, will you
damage the 7805?  Clearly the VIN is open, but the ground
pin will still be attached.  Would this push voltage
back through and screw things up?

Thanks,
Bill S.





--
The contents of this e-mail and any attachments are intended solely for
the use of the named
addressee(s) and may contain confidential and/or privileged information.
Any unauthorized use,
copying, disclosure, or distribution of the contents of this e-mail is
strictly prohibited by
the sender and may be unlawful. If you are not the intended recipient,
please notify the sender
immediately and delete this e-mail.





--
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
 www.flippers.com
"Old pinballers never die, they just flip out"

Re: Voltage regulator with alternate voltage source...

[Henk Gooijen]

-Oorspronkelijk bericht- 
From: Bill Sudbrink

Sent: Thursday, April 07, 2016 10:38 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: Voltage regulator with alternate voltage source...

If you have a circuit which is normally designed to
operate with an unregulated supply, through a regulator...
say unregulated +8 through a 7805 to a regulated +5 and
you want to test it independent of the +8 supply, if
you leave the unregulated rail unattached and put +5
switcher straight onto the regulated +5 rail, will you
damage the 7805?  Clearly the VIN is open, but the ground
pin will still be attached.  Would this push voltage
back through and screw things up?

Thanks,
Bill S.

-
It is a special situation I have never seen, but I would try to disconnect 
the output of the 7805 before connecting a foreign +5V to the circuit.
It is good practice to have a diode reverse connected from output to input 
to prevent damage to the 78xx in the case that the output voltage
gets higher than the input voltage. Normally that would not happen, but if 
you have a high capacitance at the output and the load is minimal
it could be possible when power is switched off that the input voltage 
dropped, but due to the big capacitor at the output the output voltage
did not yet drop. And then that diode in reverse from output to input comes 
into play.


Now the input is not connected, but GND and the output are ... I would have 
a look at a data sheet of the 78xx series to see what could happen

if the input is not connected, but the output is.
So, if possible, simply disconnect the 78xx output lead first.

- Henk 

Re: Voltage regulator with alternate voltage source...

[William Donzelli]

Per his description, the 7805's input will be open. It will not try to
source any current, as it will have none to give.

I suppose there might be a little leakage.

--
Will

On Thu, Apr 7, 2016 at 4:58 PM, drlegendre .  wrote:
> Err.. unless the voltage of the switcher is identical to that of the 7805,
> then one device will source current, and the other will sink it.
>
> Like putting two 6V batteries in parallel, where one is fresh and the other
> weak. Current will flow until the potentials are equalized. But with two
> regulated circuits, I don't see how equality can be achieved.
>
> Not saying it's going to smoke-out, but it does seem like a wonky thing to
> do.
>
> On Thu, Apr 7, 2016 at 3:41 PM, wulfman  wrote:
>
>> You should be just fine.
>>
>> On 4/7/2016 1:38 PM, Bill Sudbrink wrote:
>> > If you have a circuit which is normally designed to
>> > operate with an unregulated supply, through a regulator...
>> > say unregulated +8 through a 7805 to a regulated +5 and
>> > you want to test it independent of the +8 supply, if
>> > you leave the unregulated rail unattached and put +5
>> > switcher straight onto the regulated +5 rail, will you
>> > damage the 7805?  Clearly the VIN is open, but the ground
>> > pin will still be attached.  Would this push voltage
>> > back through and screw things up?
>> >
>> > Thanks,
>> > Bill S.
>> >
>> >
>> >
>>
>>
>> --
>> The contents of this e-mail and any attachments are intended solely for
>> the use of the named
>> addressee(s) and may contain confidential and/or privileged information.
>> Any unauthorized use,
>> copying, disclosure, or distribution of the contents of this e-mail is
>> strictly prohibited by
>> the sender and may be unlawful. If you are not the intended recipient,
>> please notify the sender
>> immediately and delete this e-mail.
>>
>>

Re: Voltage regulator with alternate voltage source...

[drlegendre .]

Err.. unless the voltage of the switcher is identical to that of the 7805,
then one device will source current, and the other will sink it.

Like putting two 6V batteries in parallel, where one is fresh and the other
weak. Current will flow until the potentials are equalized. But with two
regulated circuits, I don't see how equality can be achieved.

Not saying it's going to smoke-out, but it does seem like a wonky thing to
do.

On Thu, Apr 7, 2016 at 3:41 PM, wulfman  wrote:

> You should be just fine.
>
> On 4/7/2016 1:38 PM, Bill Sudbrink wrote:
> > If you have a circuit which is normally designed to
> > operate with an unregulated supply, through a regulator...
> > say unregulated +8 through a 7805 to a regulated +5 and
> > you want to test it independent of the +8 supply, if
> > you leave the unregulated rail unattached and put +5
> > switcher straight onto the regulated +5 rail, will you
> > damage the 7805?  Clearly the VIN is open, but the ground
> > pin will still be attached.  Would this push voltage
> > back through and screw things up?
> >
> > Thanks,
> > Bill S.
> >
> >
> >
>
>
> --
> The contents of this e-mail and any attachments are intended solely for
> the use of the named
> addressee(s) and may contain confidential and/or privileged information.
> Any unauthorized use,
> copying, disclosure, or distribution of the contents of this e-mail is
> strictly prohibited by
> the sender and may be unlawful. If you are not the intended recipient,
> please notify the sender
> immediately and delete this e-mail.
>
>

Re: Voltage regulator with alternate voltage source...

[wulfman]

You should be just fine.

On 4/7/2016 1:38 PM, Bill Sudbrink wrote:
> If you have a circuit which is normally designed to
> operate with an unregulated supply, through a regulator...
> say unregulated +8 through a 7805 to a regulated +5 and
> you want to test it independent of the +8 supply, if
> you leave the unregulated rail unattached and put +5
> switcher straight onto the regulated +5 rail, will you
> damage the 7805?  Clearly the VIN is open, but the ground
> pin will still be attached.  Would this push voltage
> back through and screw things up?
>
> Thanks,
> Bill S.
>
>
>


-- 
The contents of this e-mail and any attachments are intended solely for the use 
of the named
addressee(s) and may contain confidential and/or privileged information. Any 
unauthorized use,
copying, disclosure, or distribution of the contents of this e-mail is strictly 
prohibited by
the sender and may be unlawful. If you are not the intended recipient, please 
notify the sender
immediately and delete this e-mail.

Voltage regulator with alternate voltage source...

[Bill Sudbrink]

If you have a circuit which is normally designed to
operate with an unregulated supply, through a regulator...
say unregulated +8 through a 7805 to a regulated +5 and
you want to test it independent of the +8 supply, if
you leave the unregulated rail unattached and put +5
switcher straight onto the regulated +5 rail, will you
damage the 7805?  Clearly the VIN is open, but the ground
pin will still be attached.  Would this push voltage
back through and screw things up?

Thanks,
Bill S.

Data General Nova Star Trek

[jwsmobile]

A friend has a large set of paper tape which seems to be from a DG User 
group (not sure about that, but label on box sort of implies that).


The tape pile is fanfold about 10" across in a DG box specially made for 
such use.


We hope to have a reader to digitize it soon, but wonder if anyone knows 
of such a program?  We just have the labels which say that is what the 
tape has to go on.


More photos and the like later.  I know that more info would be helpful, 
but figured I'd ask first.

thanks
Jim

Re: Why do good floppy disks go bad?

[ben]

On 4/7/2016 11:11 AM, Chuck Guzis wrote:

On 04/07/2016 02:32 AM, Tor Arntsen wrote:

The problem with lifetime warranties is that they're not about the
lifetime of the owner, and they're not about the lifetime of the
product. What it means is "as long as it's a product we're still
selling" (except for those cases where it *really* is the lifetime
of the product.. in which case it means "the warranty is valid until
the product fails").



Sometimes, very rarely, it does happen the other way.  The guys at the
local auto parts store tell me about the woman who comes in about every
5 years to have her car battery replaced, free of charge, since she
bought into a promotional deal for replacement batteries "for as long as
you own your car".  IIRC, she owns a 1984 Volvo.


Radio Shack seems to have dropped the Free Batteries too.
I think they would have made more $$ with  a New Phone of the Month 
Club. Ben.

PS: You can still get tubes, just more $$$.

Re: Why do good floppy disks go bad?

[Chuck Guzis]

On 04/07/2016 04:56 AM, william degnan wrote:
> not sure if anyone mentioned this point yet, but I have found that the
> drives destroy good disks a sizable percentage of the time.  Keeping the
> heads clean and testing a drive before use with an important vintage disk
> is key to the longevity of the disk.  I also always make a backup copy of
> most every disk I use, and leave the original in a safe temp-consistent
> place.
> 

I'll go one step further and state that if you hear your drive
squealing, throw the disk away and clean the heads before you insert
another disk.  Otherwise, the problem can spread like measles.

--Chuck

Re: Why do good floppy disks go bad?

[Chuck Guzis]

On 04/07/2016 02:32 AM, Tor Arntsen wrote:
> The problem with lifetime warranties is that they're not about the 
> lifetime of the owner, and they're not about the lifetime of the 
> product. What it means is "as long as it's a product we're still 
> selling" (except for those cases where it *really* is the lifetime
> of the product.. in which case it means "the warranty is valid until
> the product fails").


Sometimes, very rarely, it does happen the other way.  The guys at the
local auto parts store tell me about the woman who comes in about every
5 years to have her car battery replaced, free of charge, since she
bought into a promotional deal for replacement batteries "for as long as
you own your car".  IIRC, she owns a 1984 Volvo.

Magazines used to offer "lifetime subscriptions", but I haven't seen
those lately.

I'm a life member of a couple of professional organizations, but I don't
know if they even exist any longer.

My water heater supposedly has a guarantee for replacement for as long
as I own my home.  I haven't had to claim a replacement yet.

--Chuck

RE: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

[Jay West]

I want to be clear... I was not saying Anke shouldn't have posted about VCF
here. His post was 100% fine and appreciated.

I just didn't want to get into a "what is classic/vintage" thread again ;)

J

Re: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

[Anke Stüber]

Hi,

On Thu, Apr 07, 2016 at 11:18:21AM -0500, Jay West wrote:
> Anke wrote...
> =
> If anybody has a nicer definition of "vintage" or 
> =
> 
> Please... not here.

no, not here of course, just send a mail to me directly or to
i...@vcfb.de.

Regards, Anke

Re: RE: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

[R SMALLWOOD]

Original message
>From : jw...@classiccmp.org
Date : 07/04/2016 - 17:18 (GMTDT)
To : cctalk@classiccmp.org
Subject : RE: VCF Europe, April 30th - May 1st, Munich + registration for VCF 
Berlin

Anke wrote...
=
If anybody has a nicer definition of "vintage" or 
=

Please... not here.

Krug Clos du Mesnil 2000

RE: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

[Jay West]

Anke wrote...
=
If anybody has a nicer definition of "vintage" or 
=

Please... not here.

Re: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

[Anke Stüber]

Hi,

On Thu, Apr 07, 2016 at 04:00:44PM +0100, R SMALLWOOD wrote:
> I'm not sure I'd be able to go to that. Its says all items have to be
> more than 10 years old

it's just a general rule we use to explain to people that their old
Windows PC isn't considered vintage. Of course there are exceptions to
this rule, like building enhancements for or replicas of vintage
hardware. For example last year Oscar Vermeulen exhibited his PiDP-8 and
KIM Uno. In case you are unsure whether your exhibition would fit you
can always contact us at i...@vcfb.de.

If anybody has a nicer definition of "vintage" or would like to help
with the translation of the website, we appreciate any help!

Regards, Anke

Re: DEC fieldguide

[Sean Caron]

On Thu, 7 Apr 2016, shad wrote:


Hello,
I'm a modest collector of DEC and PDP11 stuff, I always thank who wrote the
PDP11 field guide with the almost complete list of all the existing
boards...
Now comes the idea: could be useful having a website where the field guide
assume a graphical aspect, including pictures of the parts, descriptions,
and so on?
Of course it would be almost impossible for one alone to do all the work,
but I'm thinking of a sort of wiki, where subscripted users can upload
pictures, informations and documentations.
Maybe something similar already exists?

Thanks
Andrea



Hi Andrea,

For the case of some Q-bus boards this has already been done:

http://vaxarchive.pimpworks.org/hw/vfg/

Enjoy!

Best,

Sean

Re: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

[R SMALLWOOD]

I'm not sure I'd be able to go to that. Its says all items have to be more than 
10 years old
MY replica PDP front panels are brand new!!

Rod Smallwood




Original message
>From : stuebera...@yahoo.de
Date : 06/04/2016 - 23:56 (GMTDT)
To : cctalk@classiccmp.org
Subject : VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

Hi list,

the 17th edition of VCF Europe[0] is coming soon! It will take place on
April 30th and May 1st in Munich, Germany. Please be aware that the
information on the English version of the website might be outdated or
less detailed than on the German page, but Google Translate will help.

Also the registration for VCF Berlin[1] in October is open now. We are
looking for speakers, workshop instructors and exhibitors, both for the
regular exhibition and this year's special exhibition on computers and
languages. It will be open for visitors on Sunday, 2nd and Monday, 3rd
of October, as the 3rd October is a public holiday in Germany, but we
are thinking about inviting people to build up on Friday already and
using Saturday, 1st of October as a day just for the participants and
the community. This way there would be more time to talk and see the
other exhibitions. Maybe we could even offer advanced workshops on
Saturday. Come and visit us! Ping me if you need a place to stay.

Regards, Anke

[0] http://vcfe.org/E/index.html
[1] http://vcfb.de/2016/index.html.en

Re: Why do good floppy disks go bad?

[Maciej W. Rozycki]

On Thu, 7 Apr 2016, Tor Arntsen wrote:

> The problem with lifetime warranties is that they're not about the
> lifetime of the owner, and they're not about the lifetime of the
> product. What it means is "as long as it's a product we're still
> selling"

 Well, that's an interesting observation, and actually I find it 
reasonable even -- after all how can a supplier replace their product they 
don't have anymore?  I wish it was more clearly stated though, and then of 
course respected in all cases.

  Maciej

Re: Why do good floppy disks go bad?

[Paul Koning]

> On Apr 6, 2016, at 10:22 PM, Fred Cisin  wrote:
> 
> ...
> Entropy: Could the rust on the cookie be de-oxidizing, and turning back into 
> non-oxidized ferrous compounds? 

No.  If that were true, iron ore would spontaneously turn into iron.  
Unfortunately, that does not happen.

paul

Re: Why do good floppy disks go bad?

[william degnan]

not sure if anyone mentioned this point yet, but I have found that the
drives destroy good disks a sizable percentage of the time.  Keeping the
heads clean and testing a drive before use with an important vintage disk
is key to the longevity of the disk.  I also always make a backup copy of
most every disk I use, and leave the original in a safe temp-consistent
place.

-- 
@ BillDeg:
Web: vintagecomputer.net
Twitter: @billdeg 
Youtube: @billdeg 
Unauthorized Bio 

Re: Why do good floppy disks go bad?

[Tor Arntsen]

The problem with lifetime warranties is that they're not about the
lifetime of the owner, and they're not about the lifetime of the
product. What it means is "as long as it's a product we're still
selling" (except for those cases where it *really* is the lifetime of
the product.. in which case it means "the warranty is valid until the
product fails").

Re: Why do good floppy disks go bad?

[drlegendre .]

"Try getting a replacement for one of those Lifetime vacuum tubes at Radio
Shack."

Beat me to it. I tried that twenty years ago (with a bad quartet of 7591s)
and needless to say, got nowhere. "We haven't sold those in years!" - as if
that makes any difference, in terms of the warranty?

Sure, I can appreciate their position, but still.. they _did_ garner a
premium price for those 'Lifetime' tubes with the fancy-dancy gold pins.

And IIRC, the warranty is "For the lifetime of the equipment in which the
tubes are originally installed". So it's not as if it's limited to either
the original owner or purchaser.

Sigh, the brilliance of "Huh?!??!" ;-)

On Thu, Apr 7, 2016 at 1:25 AM, Brent Hilpert  wrote:

> On 2016-Apr-06, at 7:22 PM, Fred Cisin wrote:
> > How long were they supposed to last?
> > Will they honor those "lifetime guarantee"s?
>
>
> Try getting a replacement for one of those Lifetime vacuum tubes at Radio
> Shack.
>
>

DEC fieldguide

[shadoooo]

Hello,
I'm a modest collector of DEC and PDP11 stuff, I always thank who wrote the
PDP11 field guide with the almost complete list of all the existing
boards...
Now comes the idea: could be useful having a website where the field guide
assume a graphical aspect, including pictures of the parts, descriptions,
and so on?
Of course it would be almost impossible for one alone to do all the work,
but I'm thinking of a sort of wiki, where subscripted users can upload
pictures, informations and documentations.
Maybe something similar already exists?

Thanks
Andrea

Re: Why do good floppy disks go bad?

[ben]

On 4/6/2016 8:22 PM, Fred Cisin wrote:

Wear happens.  Particularly on directory tracks, or where you encounter
the snake in Adventure.

But, that doesn't account for the loss of data over time.

Entropy: Could the rust on the cookie be de-oxidizing, and turning back
into non-oxidized ferrous compounds?  :-)


How long were they supposed to last?
Will they honor those "lifetime guarantee"s?


You mean like the ones on Radio Shack Vacuum Tubes,a year or so before 
they all vanished from the face of the Earth.

Ben.

Re: Why do good floppy disks go bad?

[Brent Hilpert]

On 2016-Apr-06, at 7:22 PM, Fred Cisin wrote:
> How long were they supposed to last?
> Will they honor those "lifetime guarantee"s?


Try getting a replacement for one of those Lifetime vacuum tubes at Radio Shack.