[vcf-midatlantic] Fake 7400-series memory

W2HX w2hx at w2hx.com
Thu Aug 24 11:16:54 EDT 2017


I read the article about this chip. The author posited, "Why would someone go to the effort of creating counterfeit memory chips that couldn't possibly work? The 74LS189 is a fairly obscure part, so I wouldn't have expected counterfeiting it to be worth the effort. "

I would think the most logical explanation for this chip was not that someone went through the trouble of trying to pass off one chip for another, but rather that the manufacturing process simply put the wrong label on the chip. That would seem to me way more plausible than some kind of intentional subterfuge for a low demand chip in the first place. 

-----Original Message-----
From: vcf-midatlantic [mailto:vcf-midatlantic-bounces at lists.vintagecomputerfederation.org] On Behalf Of Herb Johnson via vcf-midatlantic
Sent: Thursday, August 24, 2017 11:05 AM
To: vcf-midatlantic
Cc: Herb Johnson
Subject: [vcf-midatlantic] Fake 7400-series memory

 > That was a rather interesting read. It's like a combination  > of archeology and technology. - Joe Oprysko

Right. That's what early vintage computing looks like - kinda. ;) Editorial follows, for those interested. Otherwise: thanks for this glimpse into a corner of chip-collecting. - H

Doing some Web "archeology" found the originator of the decapitated chip. It's part of a recent project by Robert Baruch which he calls "Project 54/74" and hosted on YouTube and a wiki at project5474.org, and his Twitter account. He extracts chip die from original 7400 (and the industrial/military version 5400) logic chips, for annotation and imaging; then reverse engineers the schematic. He seems to be doing other vintage-computing stuff as well, with new S-100 boards and 3D printing, very 21st century.

Tracing out chip-die sounds like rocket-science; but it's a matter of knowledge and tedium, recognizing visual patterns and following the likely logic. That's what the "fake" poster Ken Shirriff performed in his deconstruction Web post. TTL gate-level logic is usually described in 7400 documents, but not in detail. EE's in the 70's era (like me) were trained in semiconductors at almost the die level; the detailed knowledge is/was available in other textbooks for IC design specialists.

And, it's something done in the microprocessor collecting world; tracing out early CPU dies. There may well be other such projects, for other chips including TTL. And it was professionally done in the era as literal reverse-engineering; competitors looking for ways to produce copies, learn design techniques, and so on.

"Archeology and technology" overlap considerably; archeologists try to reverse engineer how structures or tools, homes, weapons were made. To me this is another example of what I call preservation by restoration and repair and Web publishing. I work at the S-100 board and chip level, not at the die level. As do others in this email list.

Herb Johnson

--
Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net


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