cmurillo at manizales.autonoma.edu.co
Fri Mar 18 10:12:49 CST 2005
I found a couple of damaged/parts-scavenged qbus boards which
I was able to identify as vt278 (decmate) cpu boards. I searched
the web and came upon documentation at bitsavers and
elsewhere. So it is pdp8-based, using the Harris chips.
1) I found the parts-layout and parts list and have been able
to identify most of the missing chips, except for the
one labeled "E63" in the parts layout schematic,
near the center of the board. This chip is not explained
in the parts list. Does anybody know what it is?
(it is the 18 pin chip to the left of pin 1 of the lower D3-6121-9A
chip, which in turn is the lowermost of the four 40 pin DIP chips
by Harris; this is when looking at the component side with
the slot tabs pointing downwards)
2) Can one use this board to run older pdp8 software?
Can one connect a terminal to the printer port with
some special cable, supply power to the board and
have the thing come back alive and talk to the terminal?
I don't have a qbus backplane, so I was just thinking about
repairing the board, repopulate it and connect power at the
(the diagrams are at http://www.bitsavers.org/pdf/dec/pdp8/cmos8/,
Carlos E. Murillo-Sanchez email: carlos_murillo at nospanners.ieee.org
Dean of Engineering, Universidad Autonoma de Manizales, Manizales, Colombia
"Western civilization... thought like the greeks, organized itself like
the romans and believed in itself like the hebrew." -- Ortega y Gasset.
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