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posted by janrinok on Friday May 19 2023, @12:23PM   Printer-friendly

http://www.righto.com/2023/05/8086-processor-group-decode-rom.html

A key component of any processor is instruction decoding: analyzing a numeric opcode and figuring out what actions need to be taken. The Intel 8086 processor (1978) has a complex instruction set, making instruction decoding a challenge. The first step in decoding an 8086 instruction is something called the Group Decode ROM, which categorizes instructions into about 35 types that control how the instruction is decoded and executed. For instance, the Group Decode ROM determines if an instruction is executed in hardware or in microcode. It also indicates how the instruction is structured: if the instruction has a bit specifying a byte or word operation, if the instruction has a byte that specifies the addressing mode, and so forth.


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  • (Score: 2) by driverless on Saturday May 20 2023, @10:11AM (2 children)

    by driverless (4770) on Saturday May 20 2023, @10:11AM (#1307119)

    The first one or two of these were interesting, but getting a front-page article every time Ken Shirriff updates his web site is starting to make him seem like Bennett Haselton on the other site. I think everyone on here is by now well aware of Ken's work in the 8086, and more than capable of going back to check the site themselves if they're that interested in it.

    • (Score: 2) by janrinok on Saturday May 20 2023, @08:25PM (1 child)

      by janrinok (52) Subscriber Badge on Saturday May 20 2023, @08:25PM (#1307172) Journal

      We will usually post the submissions that we receive from community members, all other things being equal, in preference to those gathered by bots. It might only be a handful of people commenting to them, but that doesn't reflect the number of page hits that they receive (615 different page hits for this story at the time of my replying). That is above the average for the stories in the preceding 48 hours, some of which have fewer page hits but more comments. That suggests that quite a few people are interested in TFA but that they have nothing to add to the discussion.

      At the top of this page it probably tells you how many possible submissions are currently in the queue - if it is less than 30 then we are running short. I have been away for a few days at a funeral - I haven't been running my bot. I have noted your views, and I thank you for them, however the solution is in your hands.

      --
      I am not interested in knowing who people are or where they live. My interest starts and stops at our servers.
      • (Score: 2) by driverless on Sunday May 21 2023, @01:08AM

        by driverless (4770) on Sunday May 21 2023, @01:08AM (#1307184)

        Yeah, fair enough, I'll try and contribute more...

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