----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
Are you sure it's _anything_ (rather than just being a few spare
flip-chips)? From what I remember all you have there are a few gates (and
maybe FFs) -- there's no M105 Unibus address decoder, no M782/7820/7821
Unibus Interrupt logic, no bus drivers or receivers. I can't see it's any
complete device, unless it was a bit of logic hung off (say) an DR11.
Does the backplane have an official DEC sticker on the side of the metal
frame? If so, what does it say?
This particular machine did come from a government testing lab, so it
probably had some custom stuff in it originally. The machine seems to work
fine without the flip chips installed. I looked up the M660 in the 1973-74
loginc handbook and identified it as a 'Positive Level Cable Driver'. The
description (from the book) is: "The M660 Cable Driver consists of three
NAND gate circuits each of which will drive a 100 ohm terminated cable with
M series levels or pulses of greater than 100 ns." The other cards, as you
said, are just various logic gates:
M112 - Nor Gate
M113 - Nand Gates
M116 - Six 4 input NAND Gates
M205 - General Purpose Flip Flops