
Ask HN: Changing the Behavior of a Commercial CPU - JPLeRouzic
Two decades ago it was possible for a person to tweak the microcode of Intel processors [0]<p>I wonder if this is still possible, or even better if it is possible to write our own microde to completely change the behavior of a CPU?<p>Thanks!<p>[0] <a href="https:&#x2F;&#x2F;arstechnica.com&#x2F;civis&#x2F;viewtopic.php?t=1062705" rel="nofollow">https:&#x2F;&#x2F;arstechnica.com&#x2F;civis&#x2F;viewtopic.php?t=1062705</a>
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zzo38computer
I have thought of a idea about that, where the microcode memory has ROM and
RAM, and uses a long VLIW transport-triggered (although the address bus and
data bus are also registers) self-modifying microcode with Muxcomp and each
instruction also is a jump. There is no cache, but you can store stuff in the
microcode RAM for temporary use, and there is also no out of order execution
or all of that other stuff either. I don't know if there is any such thing,
although apparently VAX does at least a few of these things (but not all of
them).

