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Thread: Mystery UVEPROM Chips (1702/1702A? 2708? or...?)

  1. #1

    Default Mystery UVEPROM Chips (1702/1702A? 2708? or...?)

    Many years ago, I purchased some white UVEPROMS cheap that look a lot like Intel 2708's from the packaging. The seller thought that they were 1702A's but wasn't sure. The problem is, other than a datecode (7829) on the bottom, they are completely unmarked. I am fairly certain that they were not physically cleaned of their markings. The datecode is in that gray-ish ink and a font that further makes me believe that it's an Intel chip. I have a real 1702A, and with a magnifying glass (only), the dies look extremely similar.

    Any ideas? I can program (with difficulty) 2708's, but 1702A's, no, and unmarked, they are nothing but curiosities.
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  2. #2
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    It [u]could]u] be a C1702A, but it's hard to tell, because the die detail doesn't show in your photo.

  3. #3

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    If they are 1702As they could be ones with some bad bits. Intel would save bad bit EPROMs to program as their preprogrammed parts ( I forget the numbers used ). They wouldn't mark them until they programmed successfully as they then mark them with the particular pattern part number. In the lab, when we need a EPROM for something, we'd scratch the paint off, erase them and see if they'd hold our particular program. If they miss a bit or two we'd throw them back in our bin for a later try with different code. That way, they were zero cost since they'd otherwise would have been tossed. I think they stopped bothering to do that when the cost of 2716 was under $5 as is wasn't worth the extra cost of handling bad part.
    They are not likely 1702 non A's as I don't think that package was ever used for non A's. They still could be 2708s though.
    Dwight

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    Grab a cheap lighted magnifying loupe online and have a look at the die. There will likely be markings somewhere as to what it is. On ICs of that vintage, I can typically pick out the markings with a 40x loupe. I've got a handful of mystery ICs that had OEM markings that turned out to be 2708s, IIRC the dice were marked 8708.

    Keep in mind that ceramic chip carriers were (and still are) available to companies for prototype/small run ICs, so there's no way to be 100% sure what's in there without a look at the die.

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