From the «1978 was a good year» department:
Feed: SoylentNews
Title: The 8086 Processor's Microcode Pipeline From Die Analysis
Author: janrinok
Date: Sun, 16 Apr 2023 18:22:00 -0400
Link: https://soylentnews.org/article.pl?sid=23/04/15/1843225&from=rss

owl[1] writes:

https://www.righto.com/2023/01/the-8086-processors-microcode-pipeline.html[2]

Intel introduced the 8086 microprocessor in 1978, and its influence still
remains through the popular x86 architecture. The 8086 was a fairly complex
microprocessor for its time, implementing instructions in microcode with
pipelining to improve performance. This blog post explains the microcode
operations for a particular instruction, "ADD immediate". As the 8086
documentation will tell you, this instruction takes four clock cycles to
execute. But looking internally shows seven clock cycles of activity. How does
the 8086 fit seven cycles of computation into four cycles? As I will show, the
trick is pipelining.

[...] The alternative is microcode: instead of building the control circuitry
from complex logic gates, the control logic is largely replaced with code. To
execute a machine instruction, the computer internally executes several
simpler micro-instructions, specified by the microcode. In other words,
microcode forms another layer between the machine instructions and the
hardware. The main advantage of microcode is that it turns the processor's
control logic into a programming task instead of a difficult logic design
task.

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Original Submission[3]

Read more of this story[4] at SoylentNews.

Links:
[1]: https://soylentnews.org/~owl/ (link)
[2]: https://www.righto.com/2023/01/the-8086-processors-microcode-pipeline.html (link)
[3]: https://soylentnews.org/submit.pl?op=viewsubsubid=59272 (link)
[4]: https://soylentnews.org/article.pl?sid=23/04/15/1843225&from=rss (link)

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