EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: johnh on October 29, 2019, 08:52:28 pm
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Cleaning out some of the crap I have hoarded and found these.
As the subject line says how old are these?
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I was easily stumped by the lack of an obvious date code in the traditional
WWYY YYWW* format, but judging by the appearance I'd say pre-1977.
Furthermore, I've never seen a 6-digit 74 code. What are they supposed to be?
EDIT - well, apparently the old TTL numbering system does include members with 4 digits after the 74, but most seem to be variations on the lower number members.
* - I'm not dyslexic, not that you couldn't tell from inverting the date code format.
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If I remember correctly, Fairchild had a habbit of dropping the decade from the date code, so they used YWW not YYWW. So these puppies would likely be from early 1971. What they are, not a clue!?
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If I remember correctly, Fairchild had a habbit of dropping the decade from the date code, so they used YWW not YYWW. So these puppies would likely be from early 1971. What they are, not a clue!?
I agree with 1971. Third and twenty-second weeks. I believe that they are three 7404 and one 7410 TTL logic devices. The '59' postfix is the fabrication facility code (sort of like the production line).
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If memory serves, Fairchild changed their package logo sometime in the early 80's. I looked at some of my old Fairchild chips and see that the newest block 'F' is from 1981 and oldest 'f' is from 1983. I don't know what logo they used on the packages in the 60's but their corporate logo above the "Traitorous Eight" picture is a slanted 'f'.
It's interesting is that the printing on the parts in question is rotated. DIPs almost always have pin 1 in the lower left when the text is upright.
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The unusual "U6A"-prefixed parts can be found in this 1974 (https://americanradiohistory.com/UK/Bernards-And-Babani/Bernards/Bernards%20BP202%20IC%20Equivalents%20and%20Substitutes.pdf) document and confirms that they are 7404s and a 7410.
Also of interest, a 1969 Fairchild databook:
https://archive.org/details/bitsavers_fairchilddldch15_20989397
...from which we find the useful phrases "Specify U3I90165XX for flat package and U6A90165XX for Dual-In-Line package, where 5XX is 51X for -55C to +125C temperature range or 59X for the 0C to +75C temperature range", and "To order Transistor-Transistor Micrologic elements specify U31XXXX-51X for Flat package and U6AXXXX51X for Dual In-Line package where XXXX is the four-digit number denoting the specific element desired."