Non CP/M OS

[Robb Bates]

Has anyone had any real success running a non CP/M OS on their RC2014 (or other) Z80 system?

I know there are several out there, and they are probably very good operating systems... but once getting past booting, what software can you run on it?

If so, can you link some software collection repositories please?

And on a side question, is it possible to run a CP/M program on a non CP/M OS?  I mean natively on the Z80, not an emulator like in Windows or something.  Examples please.

The root of this question really is the frustrating lack of subdirectories in CP/M.  I have things well organized with drives, user areas and named directories, but it's just clunky.

Robb

[Richard Deane]

You are young and spoilt. Subdirectories came later.

You can try UCSD p system . Plenty of software. Search Google.

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[Robb Bates]

Young?  lol.  I'll take that as a compliment.

I'll check it out.

Thanks,

Little Robby

[Christer Karlsson]

Am I missing something here? Is not ZSDOS another OS that is not CP/M?

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[Robb Bates]

ZSDOS apparently is CP/M with a different twist. 

Not an expert, just repeating what Google says about it

[Alan Cox]

On Sat, 9 Aug 2025 at 18:22, Robb Bates <robb...@gmail.com> wrote:

Has anyone had any real success running a non CP/M OS on their RC2014 (or other) Z80 system?

Yes I run a Unix clone on mine 8)

A lot of the older Z80 systems are difficult to port as much of the source or rights have been lost. There were a bunch of far superior to CP/M systems like TurboDOS that could do networking, shared disks, even mixed Z80 and 8086 binaries.

Other stuff is harder. In theory with the right cards you can run TRS80 programs on RC2014, also ZX81 and probably most ZX Spectrum (I've done ZX81, Spectrum I've not had time to prove but nothing in theory stops it and the same bits were done for the Memotech MTX so we know how to write the software and if need be the keyboard interceptor).

For TRS80 emulation if you pick your TRS80 config carefully you just need a card that traps I/O operations to ports E0-FF with an NMI and you can fake the rest in underlying software.

I suspect stuff like ISIS could be ported if someone really wanted but many of the other fun ones like PolyDOS are very hardware specific.

 

I know there are several out there, and they are probably very good operating systems... but once getting past booting, what software can you run on it?

Mostly CP/M software. Other systems like the Intel supplied ones generally just development tools.

If so, can you link some software collection repositories please?

And on a side question, is it possible to run a CP/M program on a non CP/M OS?  I mean natively on the Z80, not an emulator like in Windows or something.  Examples please.

Yes. The most obvious example is MSX-DOS on the MSX machines. That contains support for a Z80 bastardisation of early MSDOS with all the hooks needed for CP/M emulation for most apps. MSX2 added a lot more stuff including subdirectories, and since then users have taken it up to FAT16/32 and other things since then (Nextor etc)

Several CP/M clones also exist like ZSDOS and other machines had CP/M clones of their own specific to their hardware (eg the Husky, ProDOS on the Sam Coupe, CDOS from Cromemco and so on). There were also soviet CP/M clones. Also fun things were stuff like RDOS which emulated enough of CP/M that it could run CP/M MSBASIC on a tape only machine.

Actually running most CP/M software on top of another OS or file system is not hard. It just involves remapping the calls that are used and a tiny bit of knowledge about how CP/M stored file offsets in the FCB blocks because some apps poked them directly (DRI ones included).

The Fuzix emulation layer only maps as a single drive letter but it shows how little code is needed to remap a CP/M application onto another simple OS or file system, and you could easily do the same if you banked the Chan FATfs or similar on an RC2014 and used the same kind of remapping.

https://github.com/EtchedPixels/FUZIX/blob/master/Applications/cpm/emulator.s

The root of this question really is the frustrating lack of subdirectories in CP/M.  I have things well organized with drives, user areas and named directories, but it's just clunky.

It's actually very hard to fix because CP/M apps have no built in knowledge of paths or the possibility of their existence. Even under MSXDOS which has subdirectories CP/M apps remain clunky and locked to the current directory of the drive (as with MSDOS 1.x apps on MSDOS 2 or later). Some people made tools let you assign drive letters to subdirectories and the like but it was never possible to directly use directory paths in a CP/M app.

MSXDOS itself does provide a DOS2 (ie vaguely Unix like) path based open/close API with file handles but that requires the app is modified for or written for MSXDOS. 

Alan

[Alan Cox]

On Sat, 9 Aug 2025 at 19:12, Robb Bates <robb...@gmail.com> wrote:

ZSDOS apparently is CP/M with a different twist. 

Not an expert, just repeating what Google says about it

That would be their AI "glue cheese on pizza" search engine 8)

CP/M was a specific set of products produced by DRI and was trademarked and protected as such along with MP/M (their multi-tasking version - which can run on RC2014). ZSDOS was one of several from scratch clones that were most definitely not CP/M and back in the day anyone calling the non DRI products CP/M would probably have received a nastygram from DRI lawyers 8)

[Sławomir Zegarliński]

Hi!
I've designed a new version of an old Polish educational computer using RCbus modules. The entire operating system was originally 2 KB, but over time it was expanded to 8 KB. The monitor has many features, including debugging. I've described it on my blog in my native language, but Google translate is available. I recommend reading it.
https://klonca80.blogspot.com

Kind regards, Zegar.

[Sławomir Zegarliński]

I hadn't considered that finding articles on my chaotic blog might be difficult. I selected a few posts that might be interesting. The computer was intended for learning Z80 assembly language programming for industrial controllers.

https://klonca80.blogspot.com/2022/08/pierwszy-ca80-na-platformie-rc2014.html#more

https://klonca80.blogspot.com/2022/08/przeprowadzka-na-rc2014.html#more

https://klonca80.blogspot.com/2023/11/instrukcja-obsugi-msid-a.html#more

https://klonca80.blogspot.com/2024/02/historia-ca80.html

https://youtu.be/DX81GWKvyLs

Sorry for the confusion. Zegar.

[Doug Jackson]

I suspect the fundamental issue here is that we all have impossible large disks on our Z80 systems.  

Under original CP/M our disks would have been 128k.  And an impossibly large disks was 1Mb.

Nobody had 8 8Mb slices.    Ever..

Sub directories were implemented with marker pen on a floppy label.

Doug.

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[Richard Deane]

These days a good method could be a gotek floppy simulator and treat each image as a logical subdirectory. With dBase II to catalog your floppy images of course.

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[Alan Cox]

On Sat, 9 Aug 2025 at 23:42, 'Doug Jackson' via RC2014-Z80 <rc201...@googlegroups.com> wrote:

I suspect the fundamental issue here is that we all have impossible large disks on our Z80 systems.  

Under original CP/M our disks would have been 128k.  And an impossibly large disks was 1Mb.

An 8" DSDD floppy drive was 1MB (8" drives are double the density of 5.25/3.5" so 8" DSDD is equivalent to 5.25" HD but was 77 not 80 track).

 

Nobody had 8 8Mb slices.    Ever..

Not really true except in the early years of CP/M. 10MB 8" disks were widely available by 1981 although expensive. Sufficiently so that it was already a problem and that CP/M 3 and MP/M II (1981) both allowed much larger file systems and CP/NET was released to allow multiple client machines to share that expensive hard disk. Vendors had been shipping some 10MB+ drives and controllers aimed at the S100 type market from 1979 or so (eg the IMI 7xxx series)

The arrival of the IBM XT in 1983 pretty much cemented mass production of 5.25" 10 and 20MB MFM hard disks to a standard, and by then off the shelf single chip disk controllers were also standard so the controllers were cheap.

CP/M lasted a long time so what was true in 1974 when Kildall first offered it to Intel (who declined to buy it) and what was true in 1994/5 when the last large scale commercial product shipping with CP/M was discontinued was quite different.

 

Sub directories were implemented with marker pen on a floppy label.

Yep. Even if you had a hard disk your tools lived on it and maybe copies of the current projects. All the other stuff was on floppies (and printout).

Alan