Help Identifying Vintage Logic ICs - Page 1
Forum section: electronics / general

author: RetroHackShack
author_rank: Newbie
timestamp: March 24, 2024, 11:16:54 pm
content: I was recently lucky enough to find some old (early 70s) wire wrap boards loaded with interesting ICs. I am pretty sure these in particular are a series of logic chips, but I can't find any information on them. Does anyone recognize them?Update: Here are the ones I have been able to confirm so far.55001 = 740055002 = 740255003 = 740455005 = 741055007 = 743055008 = 744255010 = 745055011 = 747455019 = 7417955023 = 7315355024 = 7416155028 = 7416455029 = 745455032 = 740155034 = 7440

author: Benta
author_rank: Super Contributor
timestamp: March 24, 2024, 11:28:59 pm
content: Well, they're from Fairchild and seem to be aerospace parts.

author: schmitt trigger
author_rank: Super Contributor
timestamp: March 24, 2024, 11:39:36 pm
content: If you can't find any information, you might send them to user Noopy for some die pictures!By the date code, could they be some ancient DTL or RTL logic?EDIT; my previous assumption may be unlikely, as Fairchild's DTL family was the 930-series.

author: coppice
author_rank: Super Contributor
timestamp: March 24, 2024, 11:44:19 pm
content: Interesting. The sequential numbers make them seem like some kind of chip set, yet one stands out for its plastic package.

author: RetroHackShack
author_rank: Newbie
timestamp: March 25, 2024, 12:04:43 am
content: The other chips on this particular board are 74 series logic, so I am assuming these are logic chips, too. If anyone is interested in some vintage gold ceramic IC porn here is a picture of one of the other boards that is full of Intel 1101 memory.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: March 25, 2024, 12:08:07 am
content: I can't find any mention of "55xxx" series logic in Fairchild catalogs on bitsaver, so I think they are custom parts. Also in 1970 Fairchild was making 74 series logic so they would have functions not available in standard parts.

author: RetroHackShack
author_rank: Newbie
timestamp: March 25, 2024, 12:41:48 am
content: OK. Not sure why I didn't think about trying this before. I put them through the logic IC identifier on my Retro Chip Tester. The exact 74 series match varied, but the function was consistent. No guarantee that these are 100% accurate.55001 - 2 Input NAND gate55002 - 2 Input NOR gate55003 - Inverter55005 - 3 Input NAND gate55006 - 4 Input NAND gate55007 - 8 Input NAND gate55011 - Dual D-type Pos Edge Flip Flop55016 - Dual J-K Flip Flop55025 -I will continue to update this list if I find more chips in case it will help someone else.

author: EPAIII
author_rank: Super Contributor
timestamp: March 25, 2024, 09:13:02 am
content: Flip then over and see if there are any numbers on their bellies. I have seen chips with OEM numbers on top and the more common number on the bottom.

author: RetroHackShack
author_rank: Newbie
timestamp: March 25, 2024, 05:06:33 pm
content: I found some ICs on another board that were dual-marked (see pic), so I can confirm some more of these.

author: schmitt trigger
author_rank: Super Contributor
timestamp: March 25, 2024, 05:34:18 pm
content: Quote from: RetroHackShack on March 25, 2024, 12:04:43 amAny clue what this board function was? Or what product was it installed on?

author: RetroHackShack
author_rank: Newbie
timestamp: March 25, 2024, 05:46:46 pm
content: I wish I did. Whatever it was it required a lot of logic and memory. The boards are marked "Datum" and have some assembly numbers but no names or model numbers.

author: AVGresponding
author_rank: Super Contributor
timestamp: March 26, 2024, 09:32:50 pm
content: Quote from: RetroHackShack on March 25, 2024, 05:46:46 pmThe "Datum" mark is going to be a positioning marker, for use during assembly.

author: ebastler
author_rank: Super Contributor
timestamp: March 26, 2024, 09:59:19 pm
content: Quote from: AVGresponding on March 26, 2024, 09:32:50 pmAnd all lettering in the copper layer ("Datum" as well as the part numbers) will be referring to Augat's generic wire-wrap board, not to the specific circuit that was built on it. Any labelling referring to that specific circuit would be on stickers, or hand-written or printed onto the PCB, I would expect.