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Microcode (the concept) is very much older than the 1970's. Per Wikipedia ([1]) the earliest system with something like 'microcode' dates back to 1947. What i
by pwg 4y ago
Microcode (the concept) is very much older than the 1970's. Per Wikipedia ([1]) the earliest system with something like 'microcode' dates back to 1947.
What is 'special' for the 8086 is that this was a low cost microprocessor using microcode, as opposed to a multi-million dollar mainframe CPU.
[1] https://en.wikipedia.org/wiki/Microcode#History https://en.wikipedia.org/wiki/Microcode#History
edit: fix typo
- kens 4y agoYou mean the 8086, not the 8-bit 8080, right? The 8080 wasn't microcoded.
- pwg 4y agoIndeed, that was a typo. Fixed now. Thanks.
- plesner 4y agoBabbage's analytical engine used a form of microcode ~100 years earlier. Complex operations such as multiplication and division were implemented by lower-level instructions encoded as a series of pegs on a rotating barrel. Each micro-instruction ("vertical" in Babbage's terminology) could take several seconds to execute so a complete multiplication or division would take minutes.
- mikepurvis 4y agoThanks for that link! The concept of "Directly Executable High Level Language" is also kind of fascinating— seems almost like an early pitch for something like a native LISP or Java machine.