2 ms·
Wouldnt undefined instruction trap take care of that?
by rasz 4y ago
Wouldnt undefined instruction trap take care of that?
- rwmj 4y agoGood question! Did V30 trap on undefined instructions? 8086 didn't according to https://retrocomputing.stackexchange.com/questions/11327/what-did-the-8086-and-8088-do-upon-encountering-an-illegal-instruction https://retrocomputing.stackexchange.com/questions/11327/wha..., but V30 was more like an 80186 which did trap, but then 8080 emulation mode might have worked differently again. Also I don't recall how I worked out that the extended Z80 instructions were causing the problem. Debugging was a lot more complicated in those days, although programs were also much smaller.
- kens 4y agoI took a look at the V30 manual and it doesn't have an undefined instruction trap. It's an interesting chip, a superset of the 8086 as well as 8080 emulation. It includes bit manipulation instructions kind of like the Z80, along with multidigit BCD arithmetic. https://www.ceibo.com/eng/datasheets/NEC-V20-V30-Users-Manual.pdf https://www.ceibo.com/eng/datasheets/NEC-V20-V30-Users-Manua...
- rasz 4y agoV33/V53 and V33A/V53A do have them, with non A variants as non standard exception 122 http://elm-chan.org/docs/dev/v53_e.html http://elm-chan.org/docs/dev/v53_e.html mentions it. They build a cute board around it in 1998 http://elm-chan.org/works/cpu_v53/report.html http://elm-chan.org/works/cpu_v53/report.html according to MAME V40 has it as standard exception 6? https://github.com/lesbird/MAME4apple-037b5/blob/master/MAME4apple/MAME/src/cpu/nec/nec.c#L59 https://github.com/lesbird/MAME4apple-037b5/blob/master/MAME... Then again https://forum.vcfed.org/index.php?threads/nec-v20-and-cp-m.70610/post-856305 https://forum.vcfed.org/index.php?threads/nec-v20-and-cp-m.7... says no.