Re: rectangular sense core vs. diagonal

[Paul Koning via cctalk]

> On Jun 7, 2017, at 3:24 PM, Chuck Guzis via cctech  
> wrote:
> 
> On 06/07/2017 10:47 AM, Paul Koning via cctech wrote:
> 
>> 6600 core memory is documented in great detail in the training manual
>> which is on Bitsavers.  It has conventional diagonal sense lines.  It
>> does have some interesting design attributes, though.  For one thing,
>> it has pairs of inhibit wires each carrying half the inhibit current.
>> Also, there are four X inhibit and four Y inhibit lines, so you use
>> four of the address bits to select which inhibit "quadrant" is
>> driven.  The manual doesn't say why; I believe it is done to limit
>> the inductance and to keep the per-wire inductance roughly consistent
>> for the select (X and Y) and inhibit (X and Y) wires.  The drive
>> circuitry is also interesting, featuring constant currents that are
>> steered between an idling inductor and the selected wire, rather than
>> being switched on.  All these techniques seem to explain the very
>> high performance -- full read/restore cycle in about 800 ns, which in
>> 1964 was way faster than what others were doing.
> 
> How is ECS constructed?   I fooled with a lot of it back in the day, but
> never got a good look at the core planes.

I'd love to know.  I never saw the insides of ECS.  There are some documents on 
Bitsavers but none that I have seen show the ECS memory subsystem itself, 
certainly not at the circuit level.

By the way, the memory chapter of the 6600 training manual is very much worth 
reading carefully.  It has some very clever circuits in it, and trying to 
reason through in your head why things are done a certain way is a lot of fun.

paul

Re: rectangular sense core vs. diagonal

[Chuck Guzis via cctalk]

On 06/07/2017 05:02 PM, Paul Koning wrote:

> I'd love to know.  I never saw the insides of ECS.  There are some
> documents on Bitsavers but none that I have seen show the ECS memory
> subsystem itself, certainly not at the circuit level.

I found a paper from SJCC 1967 that does a pretty good job of explaining
things.  The surprising thing is that ECS is a "two wire" system.

https://www.computer.org/csdl/proceedings/afips/1967/5069/00/50690729.pdf

--Chuck

Re: rectangular sense core vs. diagonal

[Chuck Guzis via cctalk]

On 06/07/2017 10:47 AM, Paul Koning via cctech wrote:

> 6600 core memory is documented in great detail in the training manual
> which is on Bitsavers.  It has conventional diagonal sense lines.  It
> does have some interesting design attributes, though.  For one thing,
> it has pairs of inhibit wires each carrying half the inhibit current.
> Also, there are four X inhibit and four Y inhibit lines, so you use
> four of the address bits to select which inhibit "quadrant" is
> driven.  The manual doesn't say why; I believe it is done to limit
> the inductance and to keep the per-wire inductance roughly consistent
> for the select (X and Y) and inhibit (X and Y) wires.  The drive
> circuitry is also interesting, featuring constant currents that are
> steered between an idling inductor and the selected wire, rather than
> being switched on.  All these techniques seem to explain the very
> high performance -- full read/restore cycle in about 800 ns, which in
> 1964 was way faster than what others were doing.

How is ECS constructed?   I fooled with a lot of it back in the day, but
never got a good look at the core planes.

--Chuck

Re: rectangular sense core vs. diagonal

[Brent Hilpert via cctalk]

On 2017-Jun-07, at 7:12 AM, william degnan via cctalk wrote:
> Where there any computers that used a "rectangular sense" core RAM?
> Whirlwind core is diagonal.   This page describes the differences/evolution
> of the sense line.
> 
> More: http://ed-thelen.org/comp-hist/Byte/76jul.html
> 
> Were rectangular core planes used in any commercial/government computer
> that saw production activity, presumably the period 1953-1959?Whirlwind
> is known for diagonal sense planes, but was there a brief period when the
> core was "rectangular sense"
> 
>  I know core was added to Whirlwind as an
> upgrade, it did not launch into production with core.  (right?)


From what the author writes, the memory he is examining uses rectangular sense 
in a 4-wire arrangement, so the Spectra-70 would be one computer to look to.

Whirlwind started with a holding-beam memory (form of CRT storage-tube).
The problems with that inspired Jay Forrestor (whirlwind director) to come up 
with something better and resulted in the development of core memory.
That original form of core design was 4-wire with diagonal sense.

I don't know how early the rectangular sense topology was developed but with 
tighter & more complex control requirements I'd guess it was not in the 
vacuum-tube era.

'Rectangular sense' is inherent in 3-wire core memories (have to disagree with 
Jon there.) 
The sense wire being parallel to one axis of address wires makes it possible 
for it to do double duty as the inhibit wire, and so eliminate the threading of 
a fourth wire.

In my observation, the 3-wire format came in somewhere around the very late 
60s/1970.
For example, according to the maintenance manuals, the pdp-8/i (1968) is 4-wire 
diagonal sense, the pdp-8/e (1970) is 3-wire rectangular sense.
The HP2116 versions saw a similar development timeline for the memory.
I think I can say most to nearly all of the core memories of the 70s were 
3-wire and hence rectangular sense,
although I've seen one example of a smaller memory from 1974 still using 
diagonal sense.

Speculating in part, but It would make sense as the development history:

1. Original diagonal sense as the easier & more obvious way to minimise 
capacitive  & inductive coupling.

2. Somebody developed the rectangular sense, probably to help simplify 
the threading.

3. Somebody noticed the now parallel address & sense wires would allow 
combing the sense & inhibit wires, coming up with the 3-wire arrangement and 
simplifying manufacturing considerably.

Re: rectangular sense core vs. diagonal

[Paul Koning via cctalk]

> On Jun 7, 2017, at 1:01 PM, Jon Elson via cctech  
> wrote:
> 
> On 06/07/2017 09:12 AM, william degnan via cctech wrote:
>> Where there any computers that used a "rectangular sense" core RAM?
>> Whirlwind core is diagonal.   This page describes the differences/evolution
>> of the sense line.
>> 
>> More: http://ed-thelen.org/comp-hist/Byte/76jul.html
>> 
>> Were rectangular core planes used in any commercial/government computer
>> that saw production activity, presumably the period 1953-1959?Whirlwind
>> is known for diagonal sense planes, but was there a brief period when the
>> core was "rectangular sense"  I know core was added to Whirlwind as an
>> upgrade, it did not launch into production with core.  (right?)
>> 
>> 
> I think IBM LCS on the mid-scale 360s were rectangular.  I assume by 
> rectangular you mean that all wires were on a rectangular grid, parallel to 
> the select wires.  The google article on core memory shows a CDC 6600 core 
> plane that shows no sign of diagonal wires.

Are you talking about the Wikipedia article, the photo of the 6600 core memory? 
 That photo is severely misleading.  The "inset" is something entirely 
different.

6600 core memory is documented in great detail in the training manual which is 
on Bitsavers.  It has conventional diagonal sense lines.  It does have some 
interesting design attributes, though.  For one thing, it has pairs of inhibit 
wires each carrying half the inhibit current.  Also, there are four X inhibit 
and four Y inhibit lines, so you use four of the address bits to select which 
inhibit "quadrant" is driven.  The manual doesn't say why; I believe it is done 
to limit the inductance and to keep the per-wire inductance roughly consistent 
for the select (X and Y) and inhibit (X and Y) wires.  The drive circuitry is 
also interesting, featuring constant currents that are steered between an 
idling inductor and the selected wire, rather than being switched on.  All 
these techniques seem to explain the very high performance -- full read/restore 
cycle in about 800 ns, which in 1964 was way faster than what others were doing.

> I think many old core planes with big cores ran all wires on a square grid, 
> as there was plenty of window area in the cores.  When they went to smaller 
> cores and combining the sense/inhibit winding, then the diagonal wire 
> threaded more easily through the remaining window after the X and Y select 
> wires were in place.

Normal layout is what the Wikipedia article shows: wires in X/Y direction for 
the most part, cores at 45 degrees.  The sense wires normally zigzag along the 
diagonals.

One detail not often described (I found it called out in the EL-X8 training 
manual) is that the sense wire routing is done so that it passes through cores 
in alternating direction for any given row and column.  The point of doing so 
is that then the noise pulses from half-selected cores in the addressed row and 
column very nearly cancel.

On the "inset" memory with just two wires: that's prpobably CDC 6000 series ECS 
memory.  That was slow (4.8 microsecond cycle) very large memory, 488 bit 
words.  The CDC manuals describe it as "word select".  The text near that photo 
describes the approach briefly (it would be nice to have more details).  I 
vaguely remember a photo showing a large rectangular core plane -- not clear 
just how big, 256 by 488 would be a possibility, or 488 by 1024.  If so, it 
would be bits of the word arranged along one coordinate, word addresses along 
the other.

paul

Re: rectangular sense core vs. diagonal

[Jon Elson via cctalk]

On 06/07/2017 09:12 AM, william degnan via cctech wrote:

Where there any computers that used a "rectangular sense" core RAM?
Whirlwind core is diagonal.   This page describes the differences/evolution
of the sense line.

More: http://ed-thelen.org/comp-hist/Byte/76jul.html

Were rectangular core planes used in any commercial/government computer
that saw production activity, presumably the period 1953-1959?Whirlwind
is known for diagonal sense planes, but was there a brief period when the
core was "rectangular sense"  I know core was added to Whirlwind as an
upgrade, it did not launch into production with core.  (right?)


I think IBM LCS on the mid-scale 360s were rectangular.  I 
assume by rectangular you mean that all wires were on a 
rectangular grid, parallel to the select wires.  The google 
article on core memory shows a CDC 6600 core plane that 
shows no sign of diagonal wires.


I think many old core planes with big cores ran all wires on 
a square grid, as there was plenty of window area in the 
cores.  When they went to smaller cores and combining the 
sense/inhibit winding, then the diagonal wire threaded more 
easily through the remaining window after the X and Y select 
wires were in place.


Jon

Re: Serial keyboards

[Guy Sotomayor Jr via cctalk]

> On Jun 6, 2017, at 11:51 PM, Eric Smith  wrote:
> 
> On Tue, Jun 6, 2017 at 3:48 PM, Guy Sotomayor Jr via cctalk 
> > wrote:
> Yes, I’ve been dealing with the morons who strip the keyboards off of (now 
> rare) IBM 327x terminals,
> cut the connectors off and wire them up to PS/2 or USB.  May they burn in 
> hell.
> 
> I have an IBM 1389194, which is a 122-key model M, apparently for a 3192 G 
> series terminal, with APL keycaps. I do not have such a terminal; someone 
> else separated the keyboard from it.  I wouldn't mind getting a 3192 
> terminal, but I'm not willing to spend much money on one.
> 
> https://www.flickr.com/photos/22368471@N04/25859890091/ 
> 
> 
> I'm converting it into a USB keyboard, but I'm doing it in a fully reversible 
> manner.  If I burn in hell, I hope it's not because of modifying this 
> keyboard.
> 

;-)

I have that keyboard on one of my 3179 terminals.  It would be *really* useful 
if I had a 3179-G because then it could render the APL characters.  ;-)

TTFN - Guy

Re: Serial keyboards

[Alexandre Souza via cctalk]

Btw...I need a vt-340 keyboard with people willing to send it to Brazil. I
got a (uber rare here) vt-340 in nice condition, but keyboardless :(

And I still hope I'll find someday a complete vt-100 here :)

Enviado do meu Tele-Movel

On Jun 7, 2017 11:26 AM, "Pete Lancashire via cctalk" 
wrote:

I'm a Teletype collector.  I was told of someone who got two machines from
an estate. After tracking down and getting a hold of said person, he had
behind his garage a pile of the Teletypes and typewriters, on all of them
the keytops were ripped off and the machines left for scrap rusting away
while awaiting a trip to a scrap yard.
-pete



On Tue, Jun 6, 2017 at 11:51 PM, Eric Smith via cctalk <
cctalk@classiccmp.org> wrote:

> On Tue, Jun 6, 2017 at 3:48 PM, Guy Sotomayor Jr via cctalk <
> cctalk@classiccmp.org> wrote:
>
> > Yes, I’ve been dealing with the morons who strip the keyboards off of
> (now
> > rare) IBM 327x terminals,
> > cut the connectors off and wire them up to PS/2 or USB.  May they burn
in
> > hell.
> >
>
> I have an IBM 1389194, which is a 122-key model M, apparently for a 3192 G
> series terminal, with APL keycaps. I do not have such a terminal; someone
> else separated the keyboard from it.  I wouldn't mind getting a 3192
> terminal, but I'm not willing to spend much money on one.
>
> https://www.flickr.com/photos/22368471@N04/25859890091/
>
> I'm converting it into a USB keyboard, but I'm doing it in a fully
> reversible manner.  If I burn in hell, I hope it's not because of
modifying
> this keyboard.
>
> Eric
>
> "Why this is hell, nor am I out of it."
> - Christopher Marlowe, The Tragical History of the Life and Death of
Doctor
> Faustus
>
>

rectangular sense core vs. diagonal

[william degnan via cctalk]

Where there any computers that used a "rectangular sense" core RAM?
Whirlwind core is diagonal.   This page describes the differences/evolution
of the sense line.

More: http://ed-thelen.org/comp-hist/Byte/76jul.html

Were rectangular core planes used in any commercial/government computer
that saw production activity, presumably the period 1953-1959?Whirlwind
is known for diagonal sense planes, but was there a brief period when the
core was "rectangular sense"  I know core was added to Whirlwind as an
upgrade, it did not launch into production with core.  (right?)

Thanks.

Bill

RX01 drive anyone?

[william degnan via cctalk]

I still have an RX01 drive or two available.  Contact me privately if
interested.
Bill

Re: Recovered a .bas file from my old Mac Plus

[Peter Corlett via cctalk]

On Tue, Jun 06, 2017 at 08:32:14PM -0700, Michael Hunter via cctalk wrote:
[]
> Anyway, the .bas file is not plaintext, but I can see strings in it.  Here
> are the first few bytes:

That text looks like length-prefixed records:

: f900

0002:  1b00 3aaf e84f 6e65 2046 7275 636b  :..One Fruck
0010: 6564 2075 7020 7069 616e 6f00 00 ed up piano..

001D: 0c 0061   ..a
0020: 3af8 823a 20f8 8300 00   :..: 

0029:   1e 009a 2022 5374   ... "St

Whether it's an 8 bit prefix with a spurious NUL byte or 16 bit little-endian,
I couldn't say without seeing a longer example. The first line is probably a
REM statement, but I'd expect a single-byte token for it and see the two-byte
sequence AF E8. There's a spurious colon before it, but that's just the BASIC
statement separator and perhaps ": REM" was a popular idiom in that dialect.
Maybe AF is REM and the first word in your comment happened to also be a BASIC
keyword and was also (accidentally?) tokenised.

> I remember watching a documentary saying that source code used to be encoded
> / compressed.

They are usually *tokenised*, in which BASIC keywords are replaced by a single
(typically high-bit-set) character. This both reduces the memory requirements
and makes the interpreter faster. Your "fun" job is to figure out which
characters map to which tokens. Or just Google it, probably.

[...]
> begin 644 piano.bas

Bizarrely, I don't seem to have a uudecoder installed. I haven't seen a
uuencoded file in years. So my comments above are based on your short hexdump.

Re: Recovered a .bas file from my old Mac Plus

[Torfinn Ingolfsen via cctalk]

Also, emulators exist that allow you to emulate a Mac Plus on a
current computer.
Example: http://www.gryphel.com/c/minivmac/

HTH
-- 
Regards,
Torfinn Ingolfsen

Re: Serial keyboards

[Eric Smith via cctalk]

On Tue, Jun 6, 2017 at 3:48 PM, Guy Sotomayor Jr via cctalk <
cctalk@classiccmp.org> wrote:

> Yes, I’ve been dealing with the morons who strip the keyboards off of (now
> rare) IBM 327x terminals,
> cut the connectors off and wire them up to PS/2 or USB.  May they burn in
> hell.
>

I have an IBM 1389194, which is a 122-key model M, apparently for a 3192 G
series terminal, with APL keycaps. I do not have such a terminal; someone
else separated the keyboard from it.  I wouldn't mind getting a 3192
terminal, but I'm not willing to spend much money on one.

https://www.flickr.com/photos/22368471@N04/25859890091/

I'm converting it into a USB keyboard, but I'm doing it in a fully
reversible manner.  If I burn in hell, I hope it's not because of modifying
this keyboard.

Eric

"Why this is hell, nor am I out of it."
- Christopher Marlowe, The Tragical History of the Life and Death of Doctor
Faustus

Re: Recovered a .bas file from my old Mac Plus

[Chuck Guzis via cctalk]

On 06/06/2017 08:32 PM, Michael Hunter via cctech wrote:
> Hey folks,
> 
> I hope all is well. Curiosity got the better of me and I sent in an EMAC
> external HDD I had for my old Mac Plus in for recovery. I'm happy to report
> that the recovery was a success. Now I'm struggling to figure out how to
> get at the old content :)

Was that Chipmunk BASIC?  If so, versions for OS X and Linux still exist.

--Chuck