28 Oct
2015
28 Oct
'15
4:58 p.m.
While there are documents out there that describe the function of the
Educomp/Quodata TSC8-75 Timeshare System Controller for Omnibus PDP 8
machines, I have searched high and low, and there doesn't seem to be
/any/ schematics for it anywhere.
I know this was a proprietary board that did some pretty interesting
things to trap IOT, JMP, JSR, and HLT/OSR instructions on the PDP
8/e/f/m/a machines and provide additional capabilities versus DEC's
Memory Extension and Timeshare Control board.
I have a fantasy of being able to run ETOS on real PDP 8/e hardware, but
I don't have one of these boards, and they seem to be pretty much
unobtainium.
There are a few of them out there, but obviously, the owners of these
aren't in the mood to submit them for reverse engineering. Perhaps
someone out there has already done this, or someone has documentation on
the board that may include schematics that simply hasn't scanned it yet.
Bitsavers comes up with nothing under the DEC archives, and there's no
sign of Quodata or Educomp folders.
I have read the descriptions of the function of the board, and the IOTs
that make it do its things, but I just don't have the expertise on the
guts of the Omnibus PDP 8 machines to be able to take this information
and create a design for a board that performs these functions. I've
also looked at the code in SimH that emulates the functionality of the
board, but again, it isn't enough information for me to be able to
figure out how to implement it in hardware.
In any case, I think it'd be interesting to see if one of these boards
could be reproduced.
I've found some old ClassicCMP list archives that mention some stuff
about ETOS documentation and folks that worked for Educomp/Quodata that
were involved in the creation of ETOS and this board, but the thread
died over 10 years ago.
I am probably wishing for something that doesn't exist, but I figured
I'd ask anyway, as maybe someone has stumbled across some of this stuff
and just hasn't made it public yet.
Rick Bensene
The Old Calculator Museum
http://oldcalculatormuseum.com
29 Oct
29 Oct
7:57 p.m.
Hi Rick,
Call me if you can.
Paul
217 766 7690
On 10/28/15, Rick Bensene <rickb at bensene.com> wrote:
While there are documents out there that describe the
function of the
Educomp/Quodata TSC8-75 Timeshare System Controller for Omnibus PDP 8
machines, I have searched high and low, and there doesn't seem to be
/any/ schematics for it anywhere.
I know this was a proprietary board that did some pretty interesting
things to trap IOT, JMP, JSR, and HLT/OSR instructions on the PDP
8/e/f/m/a machines and provide additional capabilities versus DEC's
Memory Extension and Timeshare Control board.
I have a fantasy of being able to run ETOS on real PDP 8/e hardware, but
I don't have one of these boards, and they seem to be pretty much
unobtainium.
There are a few of them out there, but obviously, the owners of these
aren't in the mood to submit them for reverse engineering. Perhaps
someone out there has already done this, or someone has documentation on
the board that may include schematics that simply hasn't scanned it yet.
Bitsavers comes up with nothing under the DEC archives, and there's no
sign of Quodata or Educomp folders.
I have read the descriptions of the function of the board, and the IOTs
that make it do its things, but I just don't have the expertise on the
guts of the Omnibus PDP 8 machines to be able to take this information
and create a design for a board that performs these functions. I've
also looked at the code in SimH that emulates the functionality of the
board, but again, it isn't enough information for me to be able to
figure out how to implement it in hardware.
In any case, I think it'd be interesting to see if one of these boards
could be reproduced.
I've found some old ClassicCMP list archives that mention some stuff
about ETOS documentation and folks that worked for Educomp/Quodata that
were involved in the creation of ETOS and this board, but the thread
died over 10 years ago.
I am probably wishing for something that doesn't exist, but I figured
I'd ask anyway, as maybe someone has stumbled across some of this stuff
and just hasn't made it public yet.
Rick Bensene
The Old Calculator Museum
http://oldcalculatormuseum.com
10:45 p.m.
If a schematic isn't available, but a unit was made available on loan
to reverse-engineer, I'd be willing to do it. Recently I
reverse-engineered a schematic and the firmware of a Zendex ZX-200A
Multibus floppy disk controller, which replaces both the iSBC-201
single density controller and iSBC-202 double density controller used
in Intel MDS systems:
http://www.brouhaha.com/~eric/retrocomputing/zendex/zx-200a/zx-200a.pdf
https://github.com/brouhaha/zx200a-fw
30 Oct
30 Oct
7:04 a.m.
Eric Smith wrote:
If a schematic isn't available, but a unit was made available on loan to
reverse-engineer, I'd be willing to do it.
At this stage, it appears that no original schematic for this board has been uncovered.
Efforts are currently underway to reverse-engineer an actual TSC8-75 board and derive a
useful schematic. It is hopeful there will be something available relatively soon.
The particular board being reverse-engineered has a serial number of <700, so it will
not have the ESME IOT implemented, but it has been discovered that ETOS does not require
this IOT in order to run properly. ETOS will run slightly more efficiently if the board
supports the ESME IOT (6365), but it will still run just fine on the boards that don't
have the feature.
I'll try to post updates here as the project progresses.
It is my hope to be able to construct a functional equivalent of one of these boards, and
get ETOS running on my physical 8/e system. The biggest challenge is going to be
replacing the pesky SP380A (12 used on the board) and SP314A (one used on the board) chips
used for Omnibus interface, but there's a lot of discussion in the mailing list
archives about replacements that seem to work , so it shouldn't be too difficult.
-Rick
3115
days inactive
3117
days old
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