> transistors in an orderly matrix (...) forming scattered circuits connected by thin metal wires.
That's [ULA], isn't it? This tech was also known as "Gate Array", before FPGA came along.
That's [ULA], isn't it? This tech was also known as "Gate Array", before FPGA came along.
The book The ZX Spectrum ULA: How to design a microcomputer discusses [...]
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?
See footnote #5 :-)
https://www.righto.com/2020/08/inside-counterfeit-8086-proce...
As always: great stuff!
The thing is gate arrays are sort of something between a full custom part and an FPGA, they cost less per chip than a gate array, but more per chip than full custom. On the other hand NRE (up front 1 time cost)) is a lot lower than for full custom (I've built both).
These parts are mil-spec which means that their volumes will be lower, it may have made sense to build a mil-spec pad ring then spin out a range of low volume mil-spec 7400 parts from it
I am not sure that Wikipedia is out-of-date enough to have the precise terminology, but I also may be wrong.