[COFF] AT&T MAC-4 Specimens Identified

[segaloco via COFF]

Emailing with some exciting news, I've finally run down the chip code for the MAC-4 microcontroller: https://telecomarchive.s3.us-east-2.amazonaws.com/cc/pdf/circuits%20-%20integrated/circuits%20-%20integrated,%20293,%201,%201984-02-29.pdf

The 293-series of ICs are MAC-4-based 4-bit microcontrollers for various applications.  I had previously archived the datasheet here: https://archive.org/details/mac-4-specification-sheet

Well, upon finding the former document I then realized that number sounded familiar.  I have a lot of 5 various DIP-40 chips from AT&T, among them a 212C MAC-8 CPU and 229B peripheral controller.  I hadn't identified the others but two of them might just be MAC-4s (if WECo didn't have other 293 family members).  I have both a 293EC and 293ED, both in BTL 971-type ceramic DIP-40 carriers.  I am now of the assumption these are both MAC-4 chips, representing the only MAC-4 specimens I'm aware of in the hands of anyone doing computing history research.

In any case, I won't completely know until I build a checkout circuit.  No MAC-4 applications survive, nor does the documentation on the assembly language, but I have been drafting a reconstruction of it based on cross-examination of the MAC-8 and MAC-4 binary opcodes and available MAC-8 documentation, so if nothing else will plan to make a MAC-4 version of SGS pretty closely based on the MAC-8 one I'm working on.

Anywho just thought I'd share.  Like UNIX 4.O, the MAC-4 has been a bit of a white whale for me...and now I finally hold not one but two potential specimens in my hands.  I hope soon I'll be reporting back with the good news that it all works and that I've got an SGS built for it.  Whatever hardware rig I build probably won't come close to a PROMAC or MAC-Mate (the period MAC-4 devkits) but one can dream...

- Matt G.