This is an amazing project, I'm always impressed by stuff like this. I'd be very curious to know, though, if there's a market for achievements like that.
Mentioned in the article, same link too. The court documents included a diagram of the microcode format, and also a comparison of the reset sequence between Intel and NEC.
The V20 instruction set is interesting and has some very 1980s extensions. In addition to the 8080 emulation mode, it has instructions for binary-coded decimal arithmetic and bit fields.
However, NEC uses their own naming scheme which makes picking out the differences from the 8088 unnecessarily difficult. The bits are the same but the mnemonics are different. For example, they renamed all the registers (AX -> AW, SI -> IX, etc) and many opcodes (JMP -> BR, REP MOVSB -> REP MOVBK).
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[ 0.24 ms ] story [ 35.2 ms ] threadhttps://thechipletter.substack.com/p/intel-vs-nec-the-case-o...
instant speed boost for IBM PC
just pop out the 8088 and put in a $20 V20
only problems is some programs ran their clocks too fast
wow that article is amazing, I cannot believe people can reverse engineer at that level, brilliant
The V20 instruction set is interesting and has some very 1980s extensions. In addition to the 8080 emulation mode, it has instructions for binary-coded decimal arithmetic and bit fields.
However, NEC uses their own naming scheme which makes picking out the differences from the 8088 unnecessarily difficult. The bits are the same but the mnemonics are different. For example, they renamed all the registers (AX -> AW, SI -> IX, etc) and many opcodes (JMP -> BR, REP MOVSB -> REP MOVBK).
i.e. possibly Intel having some protection (copyright?) over its assembly mnemonics and register names.