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To be fair, there's Patched ROM 14, which provides the same things I'm providing. And the Nabu company's been dead for decades. But there's always a successor in interest and I'd prefer to take the safe approach rather than suddenly have some megacorp that bought out some other megacorp that...

This is certainly a case of "coder is an ID10T", but last July I tried to write a floppy disk bootloader for the Nabu that: Doesn't use the official code, because I want it copyright-clean. Can boot existing CP/M 3.1 boot disks. I coded it in two forms - one that is part of my boot ROM...

I was just about to mention "MiNT" - Mint Is Not Trac, the back-end language of Freemacs.

I want to say the 8086 has something like DJNZ using CX. Don't quote me on that one; I'm an x86 ASM n00b.

Erwot? OSX never had anything to do with Linux - you mean BSD.

I think it's just a meme that's been going around for 40 years and growing taller with the telling.

I can't remember the 0xCF (DF, EF, FF) voodoo, or where I read it. All I tried to do was read head 0, track 0, sector 1 to 0xC000 and run it. It might actually have been the Ishkur bootstrap or something, or perhaps MAME. My memory's failing me. :/

That's the code I was talking about. 😜 That's what I'm trying to fix. ;)

No dice. :( My source describes the port addresses but it's a bit cryptic.

MAME has the "pcv20" machine. Dunno how well it works.

Because then I couldn't avail myself of the existing BDOS code?

In my case, I'd implement BIOS calls as trampolines to 8086 code sitting at a fixed location at the bottom of free memory, with the default TPA being in the first free segment above that. Like, if I needed to write a character, I'd invoke a piece of 8086 code to do it through INT10. If I...

I mean exactly that.

This makes me wonder how hard it would be to make a CP/M-80 3.1 BIOS for a PC with a V20, using the normal int10, int13, etc.

I suspect it's timing. But I don't understand the hardware all that well to begin with. All I have to test against is MAME (I do have a Nabu with a FDC, but no floppy drives, so still not enough metal to test with), and apparently its emulation of the FD-1797 is a little too forgiving.

So recently I wrote some code - both ROM code and code that could be sideloaded from the virtual head end - to boot the Nabu CP/M 3.1 floppy disks. And...in MAME...it works. Problem is, it's gone Schrödinger - I had people tell me it didn't work on metal, and I haven't since had it work...

CP/M 3.1 for the MSX and Microsoft CP/M 2.2 for the Apple ][ both had a disk-based IPL that chainloaded CP/M. There was an unofficial port of 3.1 to the Apple //e that used the same basic IPL as the MSX version. Nabu CP/M 3.1 also loads a bootsector off the disk that proceeds to load the rest of...

It does Just Work®™© for me on Debian 11.

Yeah, it's been my opinion from day one that Cloud CP/M was a pile of poorly written junk (apart from, well, the CP/M bits).

Can't speak for it either; the nabu.ca and nabunetwork.com ones are the only ones I've used. I'm a complete n00b trying to punch way above my weight.