[vcf-midatlantic] Fake 7400-series memory
perkins.jason at gmail.com
Thu Aug 24 11:28:26 EDT 2017
Unless someone came across a large stash of the DTMF chips, got them for
next to nothing, and was trying to pawn them off as something useful.
On Thu, Aug 24, 2017 at 11:16 AM, W2HX via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> 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
> 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
313 355 0085
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