The chip is a Fairchild SL56660, a 5/4 NAND gate. The original design only employed four ICs but in huge quantities: this one, an alternative but slower NAND gate, 1Kx1 bipolar SRAMs (usually the Fairchild 10415FC, about 70,000 of them in the 1976 Los Alamos National Laboratory unit), and the specialized Fairchild SL82747. This chip bears a date code of 14th week 1981 and is based on emitter-coupled logic (ECL), making it very fast for the time but also very power-hungry; CMOS made ECL and MECL obsolete. The later date code can be attributed to the fact this was probably from a board installed for repair purposes.
Merry Christmas and a very happy holiday season.Saturday, December 25, 2021
See more of my general vintage computing projects,
mostly microcomputers, 6502, PalmOS, 68K/Power Mac
and Unix workstations, but that's not all. Be kind, REWIND and PLAY.
Old VCR is advertisement- and donation-funded, and what I get
goes to maintaining the hardware here at Floodgap.
I don't drink coffee, but the Mr Pibb doesn't buy itself. :-)
Thanks for reading. -- Cameron Kaiser
Hope you somehow have a restful holiday season, Dr. Kaiser.
ReplyDeleteCheers from Virginia
(unfortunately I was on-call & spent the wee hours of Xmas Day in the OR....)