4 ms·
One reason is the extra instructions are an artefact of the decode process - undefined behaviour that just happens to be useful - but woe to you if you rely on
by tempguy9999 7y ago
One reason is the extra instructions are an artefact of the decode process - undefined behaviour that just happens to be useful - but woe to you if you rely on them (although I have heard sometimes they are so useful they get publicly supported, I think something like that happened with the z80 and something to do with addressing/address space).
But here, it's weird, especially something like division which presumably isn't cheap to implement and is useful to end users. I don't get it at all.
- mysterydip 7y agoNot memory addressing, but there is this "special reset" undocumented by Zilog but discovered from a patent http://www.primrosebank.net/computers/z80/z80_special_reset.htm http://www.primrosebank.net/computers/z80/z80_special_reset....
- GoForthAssemble 7y agoI remember this 'scene' was very exciting. Pre-Internet you had to be in the in-crowd (of nerds) on bulletin boards, or at a meet up to ever find out. It felt like a free upgrade to your processor! here's another that's quite good: http://z80.info/zip/z80-documented.pdf http://z80.info/zip/z80-documented.pdf