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At Computer Science lecture we’ve been told that there’s a special code (lower that assembler) that determines behavior of CPU which is written inside CPUs ROM. It was meant that is determines what exactly every instruction in boolean logic means… That sounds quite strange – I haven’t found any kind of information about that.

Probably he meant not CPU but microcontrollers? But he told that it determines exact behavior of such kind of instructions like MOV, ADD ect. So, I am perplexed.

Or he meant any kind of PCB layout language?

Daniel Hedberg
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Ben Usman
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  • Generally not microcontrollers, burns too much power. The x86 is well known for having been microcoded, at least for the middle/latter part of its life, it may still be now. Unfortunately that leads to a myth that all processors are microcoded. They are not. – old_timer Jun 07 '11 at 13:04

1 Answers1

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Do you mean microcode?

http://en.wikipedia.org/wiki/Microcode

Raoul
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    Interestingly, the floppy disk drive was originally invented as a way of loading microcode for the IBM S/370 mainframe. http://en.wikipedia.org/wiki/History_of_the_floppy_disk – Gabe Jun 03 '11 at 12:58
  • @Gabe yes, another interesting historical fact :D – Raoul Jun 03 '11 at 12:59
  • Yes. Thank you. It seems to be microcode. So, all these SSE, MMX, 3DNow are implemented using microcode? – Ben Usman Jun 03 '11 at 13:01
  • As a php programmer, the tool I work with is very high level and allows to program in something _very close to plain english_. This stuff is in outer space for me! This aspect of computing, the low level stuff, is the part most users ( I included ) take for granted. – Stephane Gosselin Jun 03 '11 at 13:03
  • @stefgosselin I guess you're right, thought I like to know how things work :) I'm mostly self taught. – Raoul Jun 03 '11 at 13:05