20 Jul
2021
20 Jul
'21
10:13 a.m.
I worked at a company called DMA located in Amery Wisconsin during the
80's and 90's that did do core mat repair. Yes, the gal that did the
work used a scope. She replaced cores and wires. Good luck finding
someone to do that work now. If I remember the process, first the mat
was removed from the driver assembly, then the varnish was removed. Then
the mat was repaired and revarnished and then reassembled and final test
before returned to the customer.
On 2021-07-20 12:00, cctech-request at classiccmp.org wrote:
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Today's Topics:
1. Re: DEC PDP-8/e H212 core mat repair (steven at malikoff.com)
2. Re: DEC PDP-8/e H212 core mat repair (Joshua Rice)
3. Re: DEC PDP-8/e H212 core mat repair (Joshua Rice)
4. Re: DEC PDP-8/e H212 core mat repair (Tom Hunter)
5. Re: DEC PDP-8/e H212 core mat repair (Jules Richardson)
6. Re: DEC PDP-8/e H212 core mat repair (Rod Smallwood)
7. Tektronix 8002 microprocessor lab software (Jules Richardson)
8. Re: Tektronix 8002 microprocessor lab software (Zane Healy)
9. Re: Tektronix 8002 microprocessor lab software (Al Kossow)
10. Re: Tektronix 8002 microprocessor lab software (Al Kossow)
11. Re: Tektronix 8002 microprocessor lab software (Al Kossow)
12. Re: Tektronix 8002 microprocessor lab software (Jules Richardson)
13. Re: Tektronix 8002 microprocessor lab software (Jules Richardson)
14. Re: Tektronix 8002 microprocessor lab software (Zane Healy)
15. Re: Items Wanted (Jay Jaeger)
16. Re: Items Wanted (Zane Healy)
17. Re: DEC PDP-8/e H212 core mat repair (Toby Thain)
----------------------------------------------------------------------
Message: 1
Date: Mon, 19 Jul 2021 17:59:59 +1000
From: steven at malikoff.com
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Subject: Re: DEC PDP-8/e H212 core mat repair
Message-ID:
<84f709701f774aebb1a07a8bbb6eb091.squirrel at webmail04.register.com>
Content-Type: text/plain;charset=utf-8
Tom said
The SCSI2SD v5.1 should be faster than the Q-Bus. I bought several
recently, and plan to put one in my PDP-11/73. I even opted for these
for my VAXstation 4000?s. I figure I?ll use the newer ones in an
AlphaStation.
I?d also love to have one of these, preferably using SD or CF cards.
The Webster WQESD/04 card is a fantastic card, it?s only downfall is
that it works with ESDI drives, rather than SCSI, and they?re big and
loud. :-)
Zane
------------------------------
Message: 17
Date: Mon, 19 Jul 2021 18:16:28 -0400
From: Toby Thain <toby at telegraphics.com.au>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Subject: Re: DEC PDP-8/e H212 core mat repair
Message-ID: <820d43ed-e32d-4394-4038-bb662f5e6798 at telegraphics.com.au>
Content-Type: text/plain; charset=iso-8859-15
On 2021-07-19 6:06 p.m., Rod Smallwood via cctalk wrote:
I am curious if anyone has attempted to repair
(replace) a broken wire
in a
PDP-8/e H212 (MM8EJ) core mat (8 k word). The cores are not visible
without
a microscope. I cannot imagine how these were even manufactured and
wonder
if DEC service centers repaired core mat faults or if faulty boards
were
simply discarded.
CDC 6600 cores were huge in comparison and I would not hesitate to
replace
a broken core wire on those.
I have no idea how DEC made theirs but for IBM's System 360, one of
their engineers
came up with the clever idea of stretching the core wire so it necked
and broke, leaving
a work-hardened tapered point to thread the cores with.
They patented it https://patents.google.com/patent/US3314131A
(Source: page 187 of 'IBM's 360 and early 370 Systems' by Pugh et al)
On a Youtube film about the 360 they show cores being vibrated into the
correct
orientation on a jig board.
------------------------------
Message: 2
Date: Mon, 19 Jul 2021 09:40:44 +0100 (BST)
From: Joshua Rice <rice43 at btinternet.com>
To: CCtalk <cctalk at classiccmp.org>
Subject: Re: DEC PDP-8/e H212 core mat repair
Message-ID: <55e9b1e8.2735f.17abdecb557.Webtop.91 at btinternet.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
------ Original Message ------
From: "Tom Hunter via cctalk" <cctalk at classiccmp.org>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Monday, 19 Jul, 2021 At 06:33
Subject: DEC PDP-8/e H212 core mat repair
I am curious if anyone has attempted to repair (replace) a broken wire
in a
PDP-8/e H212 (MM8EJ) core mat (8 k word). The cores are not visible
without
a microscope. I cannot imagine how these were even manufactured and
wonder
if DEC service centers repaired core mat faults or if faulty boards
were
simply discarded.
CDC 6600 cores were huge in comparison and I would not hesitate to
replace
a broken core wire on those.
Best regards
Tom Hunter
I believe much of the core manufacturing for DEC minicomputers was
outsourced, but a lot of it had become much more automated by the late
60's and early 70's. I believe it was done by machine, with a tray to
hold the toroids in place, and a very fine needle-like "bobbin" that
threaded the wires through the toroids. I believe threading the cores
by
hand had become largely obsolete by the time the PDP-8 came onto the
market.
Though i can't confirm it, i highly doubt that DEC engineers would
repair core planes. These would more likely be sent back to the
manufacturer for "recycling", with the cores being recovered and
reused.
It's worth noting that most computer manufacturers appreciated the
fragility of core memory planes at the time, with most of them being
protected with either PCB's or perspex/plastic shields on top of the
core planes. In this way, it was rather difficult for a clumsy ol'
technician to put his thumb through the planes as he was servicing
machines.
Josh
------------------------------
Message: 3
Date: Mon, 19 Jul 2021 09:52:13 +0100 (BST)
From: Joshua Rice <rice43 at btinternet.com>
To: CCtalk <cctalk at classiccmp.org>
Subject: Re: DEC PDP-8/e H212 core mat repair
Message-ID: <5d5f0788.273f3.17abdf7399b.Webtop.91 at btinternet.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
------ Original Message ------
From: "Tom Hunter via cctalk" <cctalk at classiccmp.org>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Monday, 19 Jul, 2021 At 06:33
Subject: DEC PDP-8/e H212 core mat repair
I am curious if anyone has attempted to repair (replace) a broken wire
in a
PDP-8/e H212 (MM8EJ) core mat (8 k word). The cores are not visible
without
a microscope. I cannot imagine how these were even manufactured and
wonder
if DEC service centers repaired core mat faults or if faulty boards
were
simply discarded.
CDC 6600 cores were huge in comparison and I would not hesitate to
replace
a broken core wire on those.
Best regards
Tom Hunter
These patents might be enlightening. I'm sure there's others, but these
are some i've found on a quick search.
https://patents.google.com/patent/US4161037A
<https://patents.google.com/patent/US4161037A>
https://patents.google.com/patent/US3668664
<https://patents.google.com/patent/US3668664>
Josh
------------------------------
Message: 4
Date: Mon, 19 Jul 2021 19:02:25 +0800
From: Tom Hunter <ccth6600 at gmail.com>
To: Joshua Rice <rice43 at btinternet.com>, "General Discussion:
On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
Subject: Re: DEC PDP-8/e H212 core mat repair
Message-ID:
<CAALEduCP_GLHuuMG2UO3CU329-_3E=RPqzVZ+RUGC6gTVQNFow at mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Thanks Josh,
I read through both patents but struggled to fully understand what they
described.
Unfortunately patents are written in broad terms to cover as much as
possible.
It was very interesting nevertheless.
Best regards
Tom Hunter
On Mon, Jul 19, 2021 at 4:52 PM Joshua Rice via cctalk <
cctalk at classiccmp.org> wrote:
------ Original Message ------
From: "Tom Hunter via cctalk" <cctalk at classiccmp.org>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Monday, 19 Jul, 2021 At 06:33
Subject: DEC PDP-8/e H212 core mat repair
I am curious if anyone has attempted to repair (replace) a broken wire
in a
PDP-8/e H212 (MM8EJ) core mat (8 k word). The cores are not visible
without
a microscope. I cannot imagine how these were even manufactured and
wonder
if DEC service centers repaired core mat faults or if faulty boards
were
simply discarded.
CDC 6600 cores were huge in comparison and I would not hesitate to
replace
a broken core wire on those.
Best regards
Tom Hunter
These patents might be enlightening. I'm sure there's others, but
these
are some i've found on a quick search.
https://patents.google.com/patent/US4161037A
<https://patents.google.com/patent/US4161037A>
https://patents.google.com/patent/US3668664
<https://patents.google.com/patent/US3668664>
Josh
------------------------------
Message: 5
Date: Mon, 19 Jul 2021 16:50:10 -0500
From: Jules Richardson <jules.richardson99 at gmail.com>
To: cctalk at classiccmp.org
Subject: Re: DEC PDP-8/e H212 core mat repair
Message-ID: <769e6168-9024-fa20-5b9c-ed1cb91ec641 at gmail.com>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
On 7/19/21 3:40 AM, Joshua Rice via cctalk wrote:
I believe much of the core manufacturing for DEC
minicomputers was
outsourced, but a lot of it had become much more automated by the late
60's
and early 70's.
I've got a trio of planes here, two of which are from a Lockheed
MAC-16,
but the other one is made by Keronix out of Santa Monica for an unknown
machine (dated 1973, model number "P4" and p/n 816335 if that means
anything to anyone, approx 16"x16" with two 100-pin, double-sided
finger
edge connectors on 0.1" spacing).
Anyhoo, the Keronix one has a sticker on it saying it was repaired by
DMA,
inc. in Amery, WI in 1980 - which might suggest that there were third
parties around working on boards, rather than them having to go back to
the
manufacturer for repair. (I have no idea what the nature of the repair
was,
of course; maybe it was to surrounding logic rather than the mat
itself).
It's worth noting that most computer
manufacturers appreciated the
fragility of core memory planes at the time, with most of them being
protected with either PCB's or perspex/plastic shields on top of the
core
planes.
Yes, that's how all the ones I've ever seen have been. The Keronix one
has
an additional shield over the top of the entire PCB, on top of the one
protecting the cores.
Jules
------------------------------
Message: 6
Date: Mon, 19 Jul 2021 23:06:26 +0100
From: Rod Smallwood <rodsmallwood52 at btinternet.com>
To: Jules Richardson via cctalk <cctalk at classiccmp.org>
Subject: Re: DEC PDP-8/e H212 core mat repair
Message-ID: <d5251315-3f4c-3a46-e36e-71949a90c26e at btinternet.com>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
Yes most core stringing was outsourced.
By hand under magnification was used.
I cant recall any references to automation.
That would br down to the supplier.
The story I heard was at least some were done by embroidery girls in
Hong Kong
Rod Smallwood ? -- Digital Equipment Corporation? 1975 to 1985
On 19/07/2021 22:50, Jules Richardson via cctalk wrote:
On 7/19/21 3:40 AM, Joshua Rice via cctalk
wrote:
------------------------------
Message: 7
Date: Mon, 19 Jul 2021 18:03:46 -0500
From: Jules Richardson <jules.richardson99 at gmail.com>
To: CCtalk <cctalk at classiccmp.org>
Subject: Tektronix 8002 microprocessor lab software
Message-ID: <5b8f634d-93c9-22c2-fd05-6e1937767883 at gmail.com>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
Just out of interest, is the software for the Tektronix 8002
microprocessor
lab archived out there anywhere?
What I believe is one popped up on one of my Facebook groups, and it'd
be a
trek to get it even if I can arrange a good price with the current
owner -
but it sounds like the software at the site, if it still exists, is
unlikely to surface from a huge pile of detritus, so that automatically
puts things right in boat anchor territory.
There may or may not be a terminal, too; I get the impression those
were
optional (I've been told that there are two Tek terminals, I just don't
know if they're the right models for this system).
cheers
Jules
------------------------------
Message: 8
Date: Mon, 19 Jul 2021 16:11:32 -0700
From: Zane Healy <healyzh at avanthar.com>
To: Jules Richardson <jules.richardson99 at gmail.com>, "General
Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
Subject: Re: Tektronix 8002 microprocessor lab software
Message-ID: <ED3B17DB-6591-493A-B470-D940A5E18A91 at avanthar.com>
Content-Type: text/plain; charset=utf-8
You might check with the Tektronix museum, and see what they know. As
far as I know, they aren?t actually part of Tektronix.
Zane
I believe much of the core manufacturing for DEC
minicomputers was
outsourced, but a lot of it had become much more automated by the
late 60's and early 70's.
I've got a trio of planes here, two of which are from a Lockheed
MAC-16, but the other one is made by Keronix out of Santa Monica for
an unknown machine (dated 1973, model number "P4" and p/n 816335 if
that means anything to anyone, approx 16"x16" with two 100-pin,
double-sided finger edge connectors on 0.1" spacing).
Anyhoo, the Keronix one has a sticker on it saying it was repaired by
DMA, inc. in Amery, WI in 1980 - which might suggest that there were
third parties around working on boards, rather than them having to go
back to the manufacturer for repair. (I have no idea what the nature
of the repair was, of course; maybe it was to surrounding logic rather
than the mat itself).
It's worth noting that most computer
manufacturers appreciated the
fragility of core memory planes at the time, with most of them being
protected with either PCB's or perspex/plastic shields on top of the
core planes.
Yes, that's how all the ones I've ever seen have been. The Keronix one
has an additional shield over the top of the entire PCB, on top of the
one protecting the cores.
Jules On Jul 19, 2021, at 4:03 PM, Jules Richardson via
cctalk
<cctalk at classiccmp.org> wrote:
Just out of interest, is the software for the Tektronix 8002
microprocessor lab archived out there anywhere?
What I believe is one popped up on one of my Facebook groups, and it'd
be a trek to get it even if I can arrange a good price with the
current owner - but it sounds like the software at the site, if it
still exists, is unlikely to surface from a huge pile of detritus, so
that automatically puts things right in boat anchor territory.
There may or may not be a terminal, too; I get the impression those
were optional (I've been told that there are two Tek terminals, I just
don't know if they're the right models for this system).
cheers
Jules
------------------------------
Message: 9
Date: Mon, 19 Jul 2021 16:15:11 -0700
From: Al Kossow <aek at bitsavers.org>
To: Jules Richardson via cctalk <cctalk at classiccmp.org>
Subject: Re: Tektronix 8002 microprocessor lab software
Message-ID: <395e3439-3632-33ea-9579-883ad602b8e5 at bitsavers.org>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
On 7/19/21 4:03 PM, Jules Richardson via cctalk wrote:
Just out of interest, is the software for the Tektronix 8002
microprocessor lab archived out there anywhere?
I have some but it is hard-sectored so I've never tried to read it.
It's pretty unlikely anyone at the tek museum would have tried to
recover
the floppies even if they had them.
One of my 'really like to try to recover' things at CHM is we have a
bunch of floppies from
the company that designed it for Tek, but someone put a center punch
through every disk, so
I'm going to have to take them out of the jacket and try to flatten
the dent out as best as
I can.
------------------------------
Message: 10
Date: Mon, 19 Jul 2021 16:20:19 -0700
From: Al Kossow <aek at bitsavers.org>
To: cctalk at classiccmp.org
Subject: Re: Tektronix 8002 microprocessor lab software
Message-ID: <a0c2c3a7-4c74-81da-1f40-a581d3f29fda at bitsavers.org>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
On 7/19/21 4:03 PM, Jules Richardson via cctalk wrote:
Just out of interest, is the software for the Tektronix 8002
microprocessor lab archived out there anywhere?
>
It would be nice to save a complete system though, since most have
been tossed out since there is little
practical use for them now. I never had a whole one, just board sets
for various processors that I collected
over the years.
------------------------------
Message: 11
Date: Mon, 19 Jul 2021 16:25:21 -0700
From: Al Kossow <aek at bitsavers.org>
To: Al Kossow via cctalk <cctalk at classiccmp.org>
Subject: Re: Tektronix 8002 microprocessor lab software
Message-ID: <f4bafaa8-f4d9-95aa-016e-68d36d7c8b8a at bitsavers.org>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
On 7/19/21 4:20 PM, Al Kossow via cctalk wrote:
On 7/19/21 4:03 PM, Jules Richardson via cctalk
wrote:
It would be nice to save a complete system
though, since most have
been tossed out since there is little
practical use for them now.
I've collected a LOT of in-circuit emulators and microprocessor
development systems over the decades, and
I'm trying to decide right now what I'm going to do with them.
------------------------------
Message: 12
Date: Mon, 19 Jul 2021 19:53:25 -0500
From: Jules Richardson <jules.richardson99 at gmail.com>
To: cctalk at classiccmp.org
Subject: Re: Tektronix 8002 microprocessor lab software
Message-ID: <8d864579-a8be-c8b1-9734-d208d0c10bcf at gmail.com>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
On 7/19/21 6:20 PM, Al Kossow via cctalk wrote:
On 7/19/21 4:03 PM, Jules Richardson via cctalk
wrote:
>>
>> Just out of interest, is the software for the Tektronix 8002
>> microprocessor lab archived out there anywhere?
>>
>
> It would be nice to save a complete system though, since most have
> been
> tossed out since there is little
> practical use for them now.
Well sadly it's looking like game over. By the sounds of it there's a
basement full of old equipment and boards, and a scrapper out in OH has
offered $6k for the lot, sight unseen, just on the hope that they can
make
a buck on the gold and palladium content.
The next offer seems to be from someone who's planning on just dumping
it
on ebay - so if the scrapper deal falls through maybe it'll resurface
on
That Auction Site for lolprice...
This is starting to feel like one of those situations where it's a huge
shame that the original owner of this stuff didn't have a will
expressing
what should be done with it all.
------------------------------
Message: 13
Date: Mon, 19 Jul 2021 20:17:27 -0500
From: Jules Richardson <jules.richardson99 at gmail.com>
To: cctalk at classiccmp.org
Subject: Re: Tektronix 8002 microprocessor lab software
Message-ID: <a734724d-b7f5-deb8-6e1f-10e429e8f43f at gmail.com>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
On 7/19/21 7:53 PM, Jules Richardson via cctalk wrote:
Well sadly it's looking like game over. By
the sounds of it there's a
basement full of old equipment and boards, and a scrapper out in OH
has
offered $6k for the lot, sight unseen, just on the hope that they can
make
a buck on the gold and palladium content.
annnnd... right after I hit send on that, things start looking up
again.
The guy responsible for this stuff doesn't seem to want it to get
scrapped
any more than I do, and he got in touch with folks down at Cape
Canaveral
(there are various ex-NASA things in the pile), then talked to the
family
of the estate; it sounds like some of it at least might get donated to
the
collection down there.
I'm not sure about non-NASA things at this point, we'll see - but it
sounds
like there's interest now in not junking it, at least!
Jules
------------------------------
Message: 14
Date: Mon, 19 Jul 2021 19:56:29 -0700
From: Zane Healy <healyzh at avanthar.com>
To: Jules Richardson <jules.richardson99 at gmail.com>, "General
Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
Subject: Re: Tektronix 8002 microprocessor lab software
Message-ID: <DE9B0230-1D5D-4416-992D-6B60A7886F17 at avanthar.com>
Content-Type: text/plain; charset=utf-8
On Jul 19, 2021, at 6:17 PM, Jules Richardson via cctalk
<cctalk at classiccmp.org> wrote:
On 7/19/21 7:53 PM, Jules Richardson via cctalk wrote:
That?s a bit of good news!
Zane
------------------------------
Message: 15
Date: Mon, 19 Jul 2021 22:03:49 -0500
From: Jay Jaeger <cube1 at charter.net>
To: cctalk at classiccmp.org
Cc: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Subject: Re: Items Wanted
Message-ID: <9ac110f9-2407-c9ba-6ec5-d70e9fd10d26 at charter.net>
Content-Type: text/plain; charset=utf-8; format=flowed
On 7/11/2021 9:33 AM, Eric Moore via cctalk wrote:
Well sadly it's looking like game over. By
the sounds of it there's a
basement full of old equipment and boards, and a scrapper out in OH
has offered $6k for the lot, sight unseen, just on the hope that they
can make a buck on the gold and palladium content.
annnnd... right after I hit send on that, things start looking up
again. The guy responsible for this stuff doesn't seem to want it to
get scrapped any more than I do, and he got in touch with folks down
at Cape Canaveral (there are various ex-NASA things in the pile), then
talked to the family of the estate; it sounds like some of it at least
might get donated to the collection down there.
I'm not sure about non-NASA things at this point, we'll see - but it
sounds like there's interest now in not junking it, at least!
Jules Hello, I am looking for any of the following
items. I have terminals
and
assorted qbus and S100 cards for trade, or am happy to discuss payment
:).
1) Qbus scsi card
You and me both. ;) I have one - and I intend to keep it.
2) Emulex TC01
3) QBUS bus probe
4) SD2SCSI
Do you mean a device that emulates a SCSI drive with an SD card? Why
not just go out and purchase a SCSI2SD V5.1 - a little slower than the
newer ones, but works fine in my Sun, SGI and Intergraph Boxen.
I also just bought one of the less expensive Androda SCSI emulators -
designed for Macs, really, but it might work and it is relatively
inexpensive.
5) Teletype DRPE or ARPE (already have a BRPE)
paper tape punches
6) AED/tektronix/SGI/etc... graphics terminal
FYI, if you have "Pizza Boxes" then I have found that the cable
commonly
available (VGA one end, 13W3 on the other - the one with switches on
it)
works well on both Sun and SGI Boxen. Google Sun VGA 13W3 on eBay.
You probably want the one with the switches.)
7) Unfomatted pertec controller (any bus)
I have some old Pertec formatters that have no bus interface. Free to
good homes. Some were mouse houses for a while, but were subsequently
cleaned up reasonably well. Models F649-72 (2 of those) and F649-40.
Heavy to ship.
In addition, I think I have a TC031, Pertec/QBus (I think) that I
really
am not using. I tried it out once - I think the issue was that I had a
Pertec interface speed mismatch between it and the HP drive I have with
a Pertec interface (which also has issues with loading tape.) I
suspect it is formatted, however.
8) S100 jade bus probe, system monitor board, or
similar
9) Anything fabri-tek, Gould, or SEL
I have a Fabritek memory box. I think it was on a PDP-12, but am not
100% certain without going back and looking at old paperwork. I am not
sure of its condition, electrically speaking - whether it had slots for
cables, or cables coming out of it, and if the latter, whether they are
intact. It has been stored in my basement for decades, low and dray.
That would take some work to pry out of my hands.
10) blinkenlights and flippenpaddles computers,
any interesting front
panels, etc...
11) ESDI disk emulator
I am not aware of any such beasties in the wild. MFM, yes, but I
haven't seen ESDI. I would love for such a thing to exist, thinking
of
my Apollo, 3B2 and IBM RT/PC workstations.
Thank you!
-Eric
------------------------------
Message: 16
Date: Mon, 19 Jul 2021 21:00:27 -0700
From: Zane Healy <healyzh at avanthar.com>
To: Jay Jaeger <cube1 at charter.net>, "General Discussion: On-Topic and
Off-Topic Posts" <cctalk at classiccmp.org>
Subject: Re: Items Wanted
Message-ID: <3EFC578F-97F0-468A-B3F1-8E4C17094843 at avanthar.com>
Content-Type: text/plain; charset=utf-8
On Jul 19, 2021, at 8:03 PM, Jay Jaeger via cctalk
<cctalk at classiccmp.org> wrote:
On 7/11/2021 9:33 AM, Eric Moore via cctalk wrote:
Yeah, they are sort of a necessity.
Hello, I am looking for any of the following
items. I have terminals
and
assorted qbus and S100 cards for trade, or am happy to discuss
payment :).
1) Qbus scsi card
You and me both. ;) I have one - and I intend to keep it. 4)
SD2SCSI
Do you mean a device that emulates a SCSI drive with an SD card? Why
not just go out and purchase a SCSI2SD V5.1 - a little slower than the
newer ones, but works fine in my Sun, SGI and Intergraph Boxen. 11) ESDI
disk emulator
I am not aware of any such beasties in the wild. MFM, yes, but I
haven't seen ESDI. I would love for such a thing to exist, thinking
of my Apollo, 3B2 and IBM RT/PC workstations.
Yes most core stringing was outsourced.
There's more detail on early core production in the book "IBM's Early
Computers", iirc. (And possibly "A Few Good Men From Univac".)
...
Rod Smallwood ? -- Digital Equipment Corporation? 1975 to 1985
On 19/07/2021 22:50, Jules Richardson via cctalk wrote:
> On 7/19/21 3:40 AM, Joshua Rice via cctalk wrote:
>> I believe much of the core manufacturing for DEC minicomputers was
>> outsourced, but a lot of it had become much more automated by the
>> late 60's and early 70's.
>
> I've got a trio of planes here, two of which are from a Lockheed
> MAC-16, but the other one is made by Keronix out of Santa Monica for
> an unknown machine (dated 1973, model number "P4" and p/n 816335 if
> that means anything to anyone, approx 16"x16" with two 100-pin,
> double-sided finger edge connectors on 0.1" spacing).
>
> Anyhoo, the Keronix one has a sticker on it saying it was repaired by
> DMA, inc. in Amery, WI in 1980 - which might suggest that there were
> third parties around working on boards, rather than them having to go
> back to the manufacturer for repair. (I have no idea what the nature
> of the repair was, of course; maybe it was to surrounding logic
> rather
> than the mat itself).
>
>> It's worth noting that most computer manufacturers appreciated the
>> fragility of core memory planes at the time, with most of them being
>> protected with either PCB's or perspex/plastic shields on top of the
>> core planes.
>
> Yes, that's how all the ones I've ever seen have been. The Keronix
> one
> has an additional shield over the top of the entire PCB, on top of
> the
> one protecting the cores.
>
> Jules
End of cctech Digest, Vol 82, Issue 15
************************************** 
20 Jul
20 Jul
4:04 p.m.
On 7/20/21 12:13 PM, pspan via cctech wrote:
I worked at a company called DMA located in Amery
Wisconsin during the 80's
and 90's that did do core mat repair. Yes, the gal that did the work used a
scope. She replaced cores and wires. Good luck finding someone to do that
work now. If I remember the process, first the mat was removed from the
driver assembly, then the varnish was removed. Then the mat was repaired
and revarnished and then reassembled and final test before returned to the
customer.
Oh, well there you go... perhaps the board that I have was repaired by the
gal that you're talking about :-)
Unfortunately there are no initials on my board (as was often the case for
board repairs), only a date and job number.
Jules
5:15 p.m.
On 2021-Jul-20, at 4:04 PM, Jules Richardson via cctech wrote:
On 7/20/21 12:13 PM, pspan via cctech wrote:
In general comment to the topic, I have seen planar arrays ("mats") with some
number of randomly-situated wire splices in them.
These splices are in the gaps between bit arrays, not interior to a bit array (there
isn't enough space between cores).
The splices are covered in a tiny dollop of (by appearance) silicon putty for insulation.
The number of splices and consistency of appearance suggests they were done at the time of
manufacture, while the random distribution suggests they were not part of the
manufacturing intention. That is to say, the manufacturing process was itself less than
perfect and necessitated 'repairs' so to speak.
On the question of manual vs automated assembly, I take it this could involve a mixture.
For example, stringing a number of cores onto a single wire for one axis would be easy to
automate, stringing the second axis is more difficult.
The development of 3-wire topologies over 4-wire would have helped automation, or reduced
manual effort, considerably. For stringing, the really awkward aspect of the original
4-wire topology was the sense wire that angled through all the cores at 45 degrees to the
X,Y,I wires. This was alleviated in the 3-wire topology where there is just 90 degree and
parallel relations.
I worked at a company called DMA located in Amery
Wisconsin during the 80's and 90's that did do core mat repair. Yes, the gal that
did the work used a scope. She replaced cores and wires. Good luck finding someone to do
that work now. If I remember the process, first the mat was removed from the driver
assembly, then the varnish was removed. Then the mat was repaired and revarnished and then
reassembled and final test before returned to the customer.
Oh, well there you go... perhaps the board that I have was repaired by the gal that
you're talking about :-)
Unfortunately there are no initials on my board (as was often the case for board
repairs), only a date and job number. 
10:35 p.m.
On 21.07.21 02:15, Brent Hilpert via cctalk wrote:
In general comment to the topic, I have seen planar arrays ("mats") with some
number of randomly-situated wire splices in them.
These splices are in the gaps between bit arrays, not interior to a bit array (there
isn't enough space between cores).
The splices are covered in a tiny dollop of (by appearance) silicon putty for
insulation.
I have seen the same, and measured that these splices can turn highohmic. I
recovered an 8/L coremat by resoldering these splices.
21 Jul
21 Jul
7:32 a.m.
Hi Jos,
Resoldered how?
The wires are _very_ thin (I guess 0.1 mm or thinner - think of human hair)
and they are covered with some form of high-temperature lacquer which you
would have to remove first. Also the dimensions of all this stuff is
_tiny_. There is just no space to poke anything in to solder a joint.
Your average fine tipped soldering iron would be ridiculously large to even
try.
I wonder if spot welding would work using the tip of a fine needle.
Of course before you can even attempt to repair a broken wire you have to
locate the break.
Best regards
Tom Hunter
On Wed, Jul 21, 2021 at 1:36 PM jos via cctalk <cctalk at classiccmp.org>
wrote:
On 21.07.21 02:15, Brent Hilpert via cctalk wrote:
I have seen the same, and measured that
these splices can turn highohmic.
I recovered an 8/L coremat by resoldering these splices.
In general comment to the topic, I have seen planar arrays ("mats") with
some number of randomly-situated wire splices in them.
These splices are in the gaps between bit arrays,
not interior to a bit
array (there isn't enough space between cores).
The splices are covered in a tiny dollop of (by
appearance) silicon
putty for insulation.
8:33 a.m.
On 21.07.21 16:32, Tom Hunter via cctalk wrote:
Hi Jos,
Resoldered how?
These joints are located above the core-mat. I just used my tiniest tip to reheat, no
solder added.
These joints were not broken, just highohmic,? several? 100 Ohms . I am still wondering
what the exact failure was.
I did not bother removing ( or reapplying ) that laquer.
Jos
12:20 p.m.
On 7/21/21 9:32 AM, Tom Hunter via cctalk wrote:
Hi Jos,
Resoldered how?
The wires are _very_ thin (I guess 0.1 mm or thinner - think of human hair)
It's not at all scientific, but I took a photo via a loupe of one of my
core boards with a cat hair over the top a couple of years ago, and the
wires are about half the width of the cat hair; I think that likely puts
them in the region of 0.02mm or thereabouts, with the diameter of the cores
being about ten times that.
12:57 p.m.
On Jul 21, 2021, at 3:20 PM, Jules Richardson via
cctalk <cctalk at classiccmp.org> wrote:
On 7/21/21 9:32 AM, Tom Hunter via cctalk wrote:
Wire that size is readily available; I just spent 15 seconds in Google and turned up one
that sells "magnet wire" (enamel insulated copper wire) in sizes as small as
0.011 mm. You'd have to handle that stuff pretty carefully...
paul
Hi Jos,
Resoldered how?
The wires are _very_ thin (I guess 0.1 mm or thinner - think of human hair)
It's not at all scientific, but I took a photo via a loupe of one of my core boards
with a cat hair over the top a couple of years ago, and the wires are about half the width
of the cat hair; I think that likely puts them in the region of 0.02mm or thereabouts,
with the diameter of the cores being about ten times that.
7:08 a.m.
On Jul 20, 2021, at 8:15 PM, Brent Hilpert via cctech
<cctech at classiccmp.org> wrote:
...
The development of 3-wire topologies over 4-wire would have helped automation, or reduced
manual effort, considerably. For stringing, the really awkward aspect of the original
4-wire topology was the sense wire that angled through all the cores at 45 degrees to the
X,Y,I wires. This was alleviated in the 3-wire topology where there is just 90 degree and
parallel relations.
There is even such a thing as 2-wire core memory. That means no coincident current
addressing, instead each address wire directly addresses a column of cores and the sense
wires (horizontal) sense the bits in the word. CDC 6000 series ECS -- bulk core memory
used as a very fast block transfer storage -- was built that way, with 488 bit words (8
60-bit CPU words plus parity, 3.2 microsecond cycle time, 4-way interleaved to deliver a
CPU word every 100 ns CPU "minor cycle").
In the 1950s, bistable (square hysteresis loop) cores were used as logic elements. Ken
Olsen, the founder of DEC, did his MS thesis work on this. And I have somewhere an
article about a keyboard operated Morse code sending device from that era that is built
around a ferrite core shift register.
It isn't usually described this way, but a good way to think of conventional core
memory is as an array of logic elements. Each core is a three input AND gate, with the
inputs being X, Y, and not-Inhibit.
paul
21 Jul
21 Jul
6:59 a.m.
On Jul 20, 2021, at 10:04 PM, John Foust via cctalk
<cctalk at classiccmp.org> wrote:
At 12:13 PM 7/20/2021, pspan via cctalk wrote:
Perhaps because someone there started the business, did a good job, and since the field
wasn't big enough to support two companies he ended up owning the one and only core
repair company in the US.
Re an earlier comment about 3-wire vs. 4-wire topologies, if you want to see even wilder
stuff take a look at the design of the CDC 6000 core modules. It's documented in one
of the training manuals on Bitsavers. It uses a FIVE wire design, with two inhibit wires
rather than one. And the inhibit wire doesn't run through the whole plane as is
usual; there are four horizontal and four vertical inhibit wires.
The description doesn't give a reason, but my assumption for why this was done is that
the total inductance of each of the driven wires (X, Y, InhX and InhY) in the 12-bit stack
is roughly the same. That means a single driver design works for all those wires. The
other thing that's interesting is that the drivers don't switch current on and
off; instead, they switch current from an idling inductor to the wire. Again, it
doesn't say why; I assume it is for speed (short pulse duration). Certainly the
performance of those memories -- 1 microsecond read/restore cycle and under 500 ns access
time -- is astoundingly fast for 1964.
paul
I worked at a company called DMA located in Amery
Wisconsin during the 80's and 90's that did do core mat repair.
And why were they in Amery, WI - a very small town?
- John 
20 Jul
20 Jul
9:50 p.m.
On 7/20/2021 10:13 AM, pspan via cctech wrote:
I worked at a company called DMA located in Amery
Wisconsin during the
80's and 90's that did do core mat repair. Yes, the gal that did the
work used a scope. She replaced cores and wires. Good luck finding
someone to do that work now. If I remember the process, first the mat
was removed from the driver assembly, then the varnish was removed.
Then the mat was repaired and revarnished and then reassembled and
final test before returned to the customer.
There was a company started around a
lady who did the core repair (one
of two) at Microdata. They had inhouse built up from scratch cores of 8
and 16k size.? Later the Ampex core division which was sold to CDC
manufactured a 32k version.? There were also Keronix 8k which went in
Micro 800s and 1600s.? Earlier there were 4k boards for the 800s.
Anyway the company was Memtek and was located on Grand Ave in Santa Ana,
CA.? They ran into the early 80s until the married couple won one of the
early lotteries for $1m.? The lady wanted to keep working and the
operated for another 18 months when they hit another jackpot for $1m.
That was all she wrote.? I had a chance to buy the core rework
equipment, but didn't.
There was a pretty expensive micro spot welder that she used with a
microscope and a lot of skill plus some cutting devices to free the
wiring.? The patches she did (and the others I saw from the Microdata
lady that remained there) looked like they stood up in the air over the
core plane.? used an acetone soluble material to hold the patch with a
tiny dab on the patch.
The Microdata operation that manufactured 16k cores was relocated to
Puerto Rico and ran for a number of years.
The welding device as I understood it was pretty expensive and very
precise.? I saw, but didn't photograph both off the rework stations.
Somewhere in the pile because we (Microdata) manufactured core I have a
big box of sample vials dumped by a purchasing engineering guy when he
was laid off.? I think they were still buying cores, but he wasn't in a
good mood that day.
A lot of good stuff went home with me that evening as I wasn't laid of.
As one of my early exercises like that felt like a vulture, but it was
funny as I found three other guys picking thru cubicles of laid off guys
picking over goodies.? Felt pretty bad, but you gotta pick up stuff when
it presents itself.
Observation about that, was on a Friday the layoffs took place.? The
hatchet man thought that he actually had a job in charge or Engineering,
he was fired the second Friday after he terminated about 40 engineers.
(Karma).
And the slow ones that thought about the empty cubicles. took to about
Tuesday for some of them to mention in casual conversation (Gee maybe
some good stuff is left in the laid off guy's cubes / offices).? Well, Duh.
anyway a story about core and other stuff.
thanks
Jim
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days inactive
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11 comments
8 participants
participants (8)
-
bhilpert＠shaw.ca -
ccth6600＠gmail.com -
jfoust＠threedee.com -
jos.dreesen＠greenmail.ch -
jules.richardson99＠gmail.com -
jwsmail＠jwsss.com -
paulkoning＠comcast.net -
pspan＠amerytel.net