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Comment by rasz | Hacker News Reader

NEC did their own independent line of x86 clones. Apparently NEC V33 is 8086 with "instruction decode done by hardwired logic rather than a microprogrammed control store. Throughput is twice as high as a V30" (datasheet claims four times faster). V30 was their clean room RE 8086 clone and was already 10-30% faster than original.

V33 was used in PC-98 DO+, and in SOC form (NEC V53) in legendary Akai MPC3000, probably because Roger Linn's original LM-1 and LinnDrum were also full x86 PCs with custom cards.

Sadly I cant find any place that sells V33/V53, maybe could be sourced in Japan.

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I had a laptop w/ a NEC V30 (an Ultralite PC-17-02[0]) and I recall it being a very peppy machine even compared to my father's 286. I did some assembly coding on it and I liked having the 286 PUSHA/POPA instructions. I didn't know about the 8080 emulation mode that it has, too, and it kinda makes me wish I had one to play with now.

I had absolutely no idea re: the LinnDrum being a PC. That's really cool. I've never seen one in the flesh, but now I'm wondering if anybody has done conservation of the firmware. It would be a lot of fun to look at the code.

[0] http://old.chuma.org/ultralite/index.shtml

Back in the day I tried running a CP/M program on the V30 alternate instruction set. It didn't work and I eventually tracked it down to the program using one of the Z80-only LDI/LDR/LDIR block instructions. You're not supposed to use those with CP/M but because CP/M ran on many UK Z80 machines like the Amstrads, inevitably real world programs did. The V30 would have been a great way to run Z80 software [in the late 1980s] if only they'd implemented these :-)

Wouldnt undefined instruction trap take care of that?

Good question! Did V30 trap on undefined instructions?

8086 didn't according to 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.

I 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-Manua...

V33/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 mentions it. They build a cute board around it in 1998 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/MAME... Then again https://forum.vcfed.org/index.php?threads/nec-v20-and-cp-m.7... says no.

There's a bunch of homebrew 8088, V20, and V40 "XT" boards out there now. I bought a few related boards plus a V20 and V40 from (https://www.homebrew8088.com/).

Yes, Im subscribed to Elijah https://www.youtube.com/@elijahmmiller/videos

Don’t forget the discord either.

F discord, like facebook its invisible to the outside world until you join the borg and register. Never crawled, never archived, unsearchable, undiscoverable proprietary garbage.

> Roger Linn's original LM-1 and LinnDrum were also full x86 PCs with custom cards.

Did you mean during development? LM-1 does not look like a PC, though I think I do see the NEC CPU in these screemshots: https://www.matrixsynth.com/2014/06/vintage-linndrum-lm-1-sn... - of course there's more to a vintage PC than an 8086.

I went back to my notes. https://en.wikipedia.org/wiki/Linn_9000 is 8088 PC with custom 7 slot ISA motherboard and standard ram/floppy controller cards

https://www.elektronauts.com/uploads/default/original/3X/6/8...

https://www.elektronauts.com/t/the-seminal-groovebox-linn-90...

https://www.vintage-radio.net/forum/showthread.php?t=87739

http://studiorepair.com/gallery/Linn/9000/index.html

LM-1 and LM-2 were Z-80 based. Damn, cant edit my first post :( Thank you for correction.

I guess you haven't used octopart before:

https://octopart.com/upd70136al-12-nec-10428216

https://octopart.com/upd70116hcz-16-nec-18733905

https://octopart.com/upd70116c-10-nec-2270733

Contacts octopart found for this part arent real distributors, they are bottom feeding speculators. No listed price means hundreds of dollars gouging aimed at military and government contractors I cant afford.

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