Hi,
----------
> From: Tony Duell <ard(a)p850ug1.demon.co.uk>
> To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
> Subject: Re: homemade computer for fun and experience...
> Date: Sunday, April 04, 1999 10:49 AM
> True. But AFAIK the AT keyboard host interface was never implemented in
> TTL (it always used a programmed 8042 microcontroller), so it's a little
> harder to build from scratch.
We used on our mc68000 boards a 68681 DUART & and some inverters as a
keyboard interface for xt/at. Was very simple. If anybody needs it, i could
dig it out again.
cheers,
emanuel
Does anyone know where I might be able to buy some thin black foam filter
material, to replace the stuiff that was used on my Teral computers?
These systems have a large fan that draws air into the computer, and
the intake air goes through this very thin filter, in order to capture
large particles such as lint.
After 22+ years, that foam is nothing more than dust.
I would need something almost 5 inches wide, that i could then trim to
the proper shape.
-Lawrence LeMay
Mike wrote:
>> Perhaps a
>> smaller array, but with LARGE cores where the magnetic state could have
>> some visual indicators.
>How would that work? Would you have an LED for each bit or something?
Get a little bit away from magnetic storage, and you can use neon
lamps as storage elements which are self-illuminating :-).
Neon lamps - when powered by DC - have a nice memory property: They
take about 90VDC to light up, but after they light up they'll stay on
until the voltage drops below 60VDC or so. Only problems are:
1. The thresholds can vary greatly from unit to unit.
2. The thresholds will vary depending on ambient light, as well.
Property 2 above can be used to build oscillators out of pairs
of neons, as a matter of fact...
Tim.
I got this from a guy that used to use the HP 9845 calculator and thought
this group might be interested.
>
>On Thu, 29 Apr 1999, Joe wrote:
>> What kind of work did you do with the 9845? Do you still have anything
>> for them?
>
>Joe,
>
>There's no trace of anything to be found...not even for the HP 9000/520
>used to migrate some of my applications. Let's see if you'll regret
>asking me what I did with it? :-)
>
>I actually used the 9845B (Model T) for Space Shuttle flight support
>(STS-2 through STS-24). I worked at Rockwell International Space Systems
>Division in Downey, California (now owned by Boeing). I started out in
>1979 doing bean-counting work. I wrote BASIC programs that create bar
>charts, plots, and tabulated data for the Flight Systems Design and
>Performance department. My manager, Bill Schleich, was the one who
>developed the shuttle's roll maneuver shortly after lift-off.
>
>Most (99.9%) of the engineers were IBM/TSO die-hards because they were
>old Apollo guys. They considered the HP 9845 to be a toy, but they were
>really afraid of it. Some of those guys preferred to use a printable
>tele-type terminal over CRTs!
>
>On the first shuttle flight there was unexpected lofting of the vehicle
>that we didn't account for in our trajectory predictions. Finally an
>engineer named David Pearson was able to trace the problem down to us not
>having up-to-date atmospheric data (our mainframe trajectory analysis
>programs used montly weather tables).
>
>Bill Schleich was also Dave Pearson's manager and he appreciated the
>power and versatility of the microcomputer...it helped that I impressed
>him with fancy graphics on the internal thermal printer (mainframe
>hardcopies of graphics had to be trucked from Seal Beach - about 20 miles
>away).
>
>Previously, I crossed-over to doing some small engineering studies where
>I'd plot data, etc., using the 9845. But the big project was for the
>flight support task! There was a lady named Kathy O'Connor who did some
>cool graphics with the robotic arm against a stunning line-drawing of the
>shuttle in X-Y-Z drawings.
>
>Anyway, to shorten this story, we had the launch site send us FAXes of
>their weather balloon data (no FTP in those days) for weeks, days, hours,
>and up to 15 minutes before launch. We had an HP 9872A plotter that also
>had a digitizer sight. I wrote an interactive program to have an
>engineer align the FAX on the plotter's plate and digitize points along
>the different data lines.
>
>The points were stored in arrays and fed to a cubic-spline interpolation
>program to recreate the line with more (smoother) points. The output was
>formatted into lines to be uploaded to the IBM mainframe where our big
>number-crunching trajectory analysis (M-50) program ran...it was much too
>large for the 9845 to even dream of running.
>
>The data went out over a GTE 300-baud modem that was about as large as
>one of today's VCRs. HP provided the (BASIC) software to do the actual
>file transfer and communications with the mainframe. Someone else wrote
>the programs on the mainframe to capture the uploaded data for feeding
>into the M50 program.
>
>When the M50 finished, it put the data back into tabulated form and
>downloaded it, one line at a time, to the HP. I wrote a suite of
>programs that read in the captured data and parsed it into data arrays
>which were plotted on the CRT for quick "DUMP GRAPHICS" snap-shots. We
>also used the 9872 4-color plotter for comparison plots but the thermal
>printer plots were needed quickly.
>
>Believe it or not, the process was fast enough that we once actually had
>plots for T-15minute winds in time to run downstairs in Rockwell's
>mission control room (3rd or 4th backup to NASA's MC in Houston) and see
>a live launch on live NASA video feeds, including infra reds.
>
>After about the 5th shuttle flight, I was no longer on-call and other
>engineers (all older than me because I was only 21 in 1981...I started
>programming professionally right out of high school) were following my
>procedures. I continued to make modifications for new features, etc.,
>until the 10th flight...I wrote every single byte of code for that suite
>of programs except for the package to communicate over the modem!
>
>I had transferred to Seal Beach a few flights before Challenger
>exploded. When I heard about it, I called one of the engineers
>responsible for the "Day of Launch Flight Support Effort" and he told me
>that that was the first flight that they didn't run the program (except
>for STS-1 of course because we didn't know we needed it).
>
>They wouldn't have seen anything strange even if they had run the
>program...but I like to imagine that my code would've warned them! :-)
>
>It's been a long time since I had a chance to brag about that. Thanks
>for asking. BTW, I was the system administrator for that particular
>9845. There were at least 3 others managed by different groups. I had
>access anytime I wanted or needed it. As a result, I ignored the Apple
>II, IBM PC, etc., until I migrated to the HP 9000/520.
>
>But even with the 9000/520 being such a step up, I bought an Amiga in
>1986 and have been in love with Amigas ever since!
>
>Visit http://www.amiga.com or http://www.amiga.de if the first one is
>down.
>
>Later,
>David
>
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>
Hi all,
I went scrounging today and found some interesting cards. A picture of
the first one is at "http://www.intellistar.net/~rigdonj/card1.jpg" and a
picture of the second is at "http://www.intellistar.net/~rigdonj/card2.jpg".
The first one is interesting because it has a list on the right side that
appears to be a list of memory locations and op codes. It's hard to see in
the photo but the first column is labeled CNT. (count?). Most of the ICs
are dated 1972. The only other markings on the card is "TERADYNE A 794" and
"Made in USA".
The second one is a core memory board that I *think* may be for a Data
General computer. I picked up several of these and they're all made by
Dataram Corporation and appear to date from 1972. Their part number is
3010290. I took the cover off of one. Man, the cores in these are tiny!
Can anyone identify them?
Joe
I finally borrowed a digital camera to photograph the damage to my PDP-8/L
parity core stack. The damage is more extensive than I remember. There
are the two main areas, but in addition, there are single bits that are
missing here and there over the entire area. I do not think it is possible
to repair this board without rewiring at least the four core mats on this
PCB in toto... that's 128x128 cores for the folks keeping score at home. The
wire density is approx 32 per inch. Much work. I won't be doing this anytime
soon.
Here's some photos of that stack I got back in '82 with a partial PDP-8/L
http://www.infinet.com/~erd/retrcomputing/pdp8/pix/coreassy.jpg - external view
http://www.infinet.com/~erd/retrcomputing/pdp8/pix/coremat1.jpg - one bad mat
http://www.infinet.com/~erd/retrcomputing/pdp8/pix/coremat2.jpg - another one
Thanks for all the responses to my original questions. I'm somewhat gratified
to see that the can of worms that this thread opened has been strangely on
topic. I'm especially interested in hearing the results of the #2 nut core,
if it's suitable for display purposes.
-ethan
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I have a lot of the kid's computers, (Atari, Commodore, CoCo, etc), which
I am trying to keep alive. Does anyone know if I can substitute high
quality music tapes in place of computer tapes? Or where I can still
find computer cassette tapes for sale?
Stephanie
--- Lawrence Walker <lwalker(a)mail.interlog.com> wrote:
> Doing a casual dumpster dive this eve and found a box with
>
> Vic-1520 Colour Printer Plotter. NIB including manual and cables. Unopened
> tube containing the 4 colour nibs. Dont know if they're dried out but
> they're water-based.
Huh? My 1520 uses ballpoint nibs.
Does anyone have any software for this? Somewhere on a disk, I wrote
a BASIC program to plot a function that resembles a black-hole on a
spacetime grid (and the unknown mass coordinates for Starcross), but
I have never run across any other programs for this device.
Does anyone out there have any software for it? (I don't recall seeing
any on ftp.funet.fi).
> What looks to be a 1/2 ht. 5 1/4 Apple ll floppy in a 1541 case usual All
> cable but with a different non-apple controller card inside ??
Please describe this more fully. The Spartan Mimic was "the" Apple ][
emulator for the C-64. One of its "features" was a board that sat between
the drive cables and the 1541 PCB that used relays to cut over certain
signals, and also provided for a 20-pin Apple disk connector. You could
stick an Apple disk in the 1541, read it from the Apple side, then swap disks
and read a C= disk from the C-64 side. AFAIK, the 1541 board was not
required, except perhaps as a way to tap power (i.e., the Spartan board was
essentially an Apple Disk ][ to bare-drive interface/analog board.
I was a beta-tester for the Mimic in, ISTR, 1986 or 1987. It was too little,
too late, for too much money. I did get to keep the unit. I still have the
case (empty) and the PSU (recycled into powering external SCSI disks), but
I can't seem to locate any of the innards (I think it died after a while).
My "greatest" accomplishment with it was attaching a real Apple disk for
D0 and playing Spellbreaker on the Apple at the same time as Enchanter on
the C-64, using the same keyboard and monitor, switching between the two
CPUs when one was loading the next part of the game. The documentation
described being able to write programs on each CPU that could talk through
a register window and do some multiprocessing, but I never wrote any nor saw
any for it.
Cool hardware. Dunno what you found, but it _might_ be a former part of one
of those.
-ethan
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