Further to my earlier message today, something else to go:
DECmate I / VT278 monitor & CPU
This is the VT100 monitor/housing with the 6120-PDP8-microproc-based
CPU board in one of the logic slots.
Sadly, missing the keyboard and floppies unit, so it's not complete.
IIRC, I faked a keyboard-present signal at the keyboard-jack some time
ago and got it to produce some boot text on the screen.
See for example: http://so-much-stuff.com/pdp8/decmateI/decmateI.php
. . found my notes about it from 2011:
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DEC DECMate VT278-AC
1983
System:
• LSI PDP-8 in VT100 case.
• 6120 microprocessor (D1-6120-9 8)
• 6 * SIP memory modules w 4 chips each (21-17559-AA / 8252 DP)
• 2 * 6402 (UART)
• 2 * 6121 (PIO)
• SND 5027 D (video controller)
Pros & Cons:
• CON: Missing disk drive.
• CON: Missing keyboard.
2011 Jul: Powered up. PWR-OK and CPU-OK LEDs lit, CRT filament lit. No raster.
Schematic obtained from bitsavers. No video or sync signals from processor
board to monitor board. CG CHAR CLK to CRT Controller chip is present (1.5MHz),
but no sync signals out from CRT Controller. ROM, CPU, CRTC socketed chips
rocked for contact, no change. CRT Controller may not be getting initialised in
initial ROM boot process.
Connecting ring (data) to tip (+12V) on keyboard connector after power-up
brings up SET-UP message and flashing cursor after several seconds.
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