> From: Paul Birkel
> Apparently the VT20 used the M792-YK as its bootstrap; the Field Guide
> is silent regarding the boot device and M792 documentation stops
> earlier in the series of variants.
An M792-YK recently sold on eBait; I didn't get it, but I did manage to get
the seller to put up good photos of the board, so was able to dump the
contents.
I didn't fully disassamble the program, but it was clearly something serial
line related. With the VT20 info, it's now clear what it was for. It should be
pretty easy to fully disassamble, and work out the protocol.
I have the dump of the contents if anyone has a use for them.
Noel
> From: Charles Morris
> my last couple of posts don't seem to be showing up?
I see several posts from you.
To check suspected failures, look in the archive:
http://www.classiccmp.org/pipermail/cctalk/
because just because you're not getting a personal email copy, doesn't mean
it didn't go out to the list.
E.g. you may have the 'Receive your own posts to the list?' option in your
CCTalk subscription disabled.
Noel
>On 8/10/19 8:33 AM, Charles via cctalk wrote:
>> I also scrubbed off the black anti-reflective coating since it was
>> significantly scratched and peeled anyway.
>
>um.. you didn't remove the aquadag from the outside of the crt, did you?
No worries Al, I got my EE in '81 back when CRTs were still in use and I
know how they work ;)
I was referring to the translucent stuff on the (removable) glass implosion
plate itself, designed to reduce light reflection, not the 'dag.
Some say that black sheer pantyhose can be used to recreate the same effect,
or a 3M Privacy Screen.
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I decided just to fire it up and see if anything blew... it issued the
expected beep as it came up.
Set the switch to half-duplex and it does actually echo bell (Ctrl-G) and I
can see the screen moving as I type!
But there is some kind of garbage every other row, although the cursor
moves and the screen will "clear" (except for the 12 rows of garbage).
Power supply is 5.11 volts. So far so good.
Unfortunately the screen rot is even worse than I thought - the PVA layer is
so opaque and bubbled it looked like cottage cheese once removed, and I
can't make out what characters are on the CRT... I took the monitor out
(very easy disassembly). I didn't even have to use a heat gun or a hot wire,
just started at one corner, applied a steady and gentle pull, and it came
off in one sheet with a giant sucking sound.
That oily mess took a while to clean up. I also scrubbed off the black
anti-reflective coating since it was significantly scratched and peeled
anyway.
Now waiting for the bead of clear silicone (around the outside of the plate
only) to cure. I'll make sure it's air tight so no black dust will get in
there by electrostatic attraction.
I can fix the RAM problem once I can see what is actually on the screen! ;)
Also the wire bracket with threaded ends that holds the flyback to the
monitor chassis is missing one end entirely, so I need to fix that (keep the
core halves firmly together).
Looks like I didn't get TOO bad a deal for $200 shipped, especially with
upper-case installed.
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Hey all --
Got a PDP-8/A at VCFW this past weekend. It's an OEM model sans programmer
panel and was apparently used in a CNC application. It contains a board
I'm trying to ID. It says "PDP-8/A CONSOLE ROM" on it and has no other
identifying marks other than a logo on the back. See the pictures here:
http://yahozna.dyndns.org/scratch/pdp-8/8aconsole1.jpghttp://yahozna.dyndns.org/scratch/pdp-8/8aconsole2.jpg
<http://yahozna.dyndns.org/scratch/pdp-8/8aconsole1.jpg>
None of the braintrust at VCF were able to identify this mark. I'd guess
that the board provides a simple ODT interface or something similar. The
three ICs in the upper-left with the handwritten labels are 82S129 256x4
bipolar PROMs. They're not socketed so I haven't read them in yet. The
8/A's gonna need some TLC before I dare power it on...
I'm mostly curious if anyone can ID the logo -- it would be interesting to
know who made this thing.
Thanks!
Josh
I bought an ADM-3A on ebay. The monitor and the circuit board/keyboard are
>from two different terminals - confirmed by hand-engraved serial numbers on
the halves that don't match.
Not to mention the two different case colors (pale blue top, blue bottom)!
But it does have the lower-case option already installed :)
Anyhow, there appears to be some breakdown of the CRT implosion plate
silicone (screen rot). I've read about this problem before, so no real
surprise
It seems to be turning into brown "goop" which has run down onto the circuit
board.
Do I need to remove the goop before powering it up? Or is it nonconductive
and hopefully noncorrosive, so it can wait until I remove the implosion
plate and fix it?
thanks
Charles
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https://mvsevm.fsf.net
Currently, the TOPS-10 guest account (42,42) and the Unix v7 account dmr have no passwords.
Please treat the dmr account respectfully.
I will get to account requests?eventually, probably. TImeliness is not guaranteed. All systems are hosted on Raspberry Pis (the 36-bit ones on a Pi 3B+ and the 16-bit and 32-bit ones on a Pi 2B+) on Debian Buster. Absolutely no guarantee of availability or usability is made.
Adam
I am being offered some sealed Sun memory modules, PN 501-3050. These are
512MB compatible with:
* Compatible with Sun Blade 1000 with 600MHz CPU, 1000 with 750MHz
CPU, 1000 with 900MHz CPU, Blade 1000 Workstation, 2000 Blade 2000 with
900MHz CPU, Blade 2000 with 1.015GHz CPU, Blade 2000 with 1.05GHz CPU, Blade
2000 with 1.2GHz CPU, Blade 2000 Workstation, Fire 12K with CPU 900MHz, Fire
12K with CPU 1.05GHz, Fire 12K with CPU 1.2GHz, Fire 15K with CPU 900MHz,
Fire 15K with CPU 1.05GHz, Fire 15K with CPU 1.2GHz, Sun Fire E20K, Fire
E25K, 280R (A35), 3800, 4800 (750MHz), 4810, 6800, Netra 20 (N28).
Apparently they must be installed in sets of 4. Is anyone interested in
these?
Cindy Croxton
Electronics Plus
1613 Water Street
Kerrville, TX 78028
830-370-3239 cell
sales at elecplus.com
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