From that article:

  The book The ZX Spectrum ULA: How to design a microcomputer discusses [...]
 

I had no idea such a book even existed. Now I am really curious about what other hidden gems exist on your bookshelf.

I was intrigued, thinking that someone had managed to clone an 8086 with a gate array. What a disappointment.

I've read that some fake sound chips from eBay actually used a gate array. Not original parts, not a 100% equivalent drop-in, but close enough to work & convince most buyers. Don't know if true but sounds plausible. And if so, a (relatively) simple cpu wouldn't be much of a stretch.

Ken's article doesn't mention it, but there's another reason to use a gate array: pre-fabrication, and through that, easier stock-keeping.

Say you have ~100 different IC's like the one described. One could then do all the manufacturing steps to produce eg. 100k of those gate arrays, except the last fabrication step. And possibly keep a large stock of those 'blank' gate arrays.

Then (when it's known which of those 100 IC's is needed), apply only the last production step to those 'blanks', and presto: selected IC ready - in large volume if needed. Or produce IC's where original part has become hard-to-find.

For a mil-spec part, that flexibility might be among reasons to go for a gate array.

These days, something like a fuse-based FPGA might be used instead?

> Ken's article doesn't mention it

See footnote #5 :-)

Ah, righto! Also I see you elaborated more on this aspect in article on that fake 8086. For anyone interested:

https://www.righto.com/2020/08/inside-counterfeit-8086-proce...

As always: great stuff!

Ken's footnotes are usually my favorite part of his articles!