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posted by janrinok on Sunday April 16 2023, @10:22PM   Printer-friendly

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

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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  • (Score: 2) by janrinok on Tuesday April 18 2023, @07:15PM

    by janrinok (52) Subscriber Badge on Tuesday April 18 2023, @07:15PM (#1301973) Journal

    Owl.

    I have read it!

    Jan

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    I am not interested in knowing who people are or where they live. My interest starts and stops at our servers.
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