Native CP/M

From: Hans Franke <>
Date: Tue Apr 9 14:09:48 2002

> I'm trying to build a development platform for my Imsai. I've tried various
> CP/M emulators but haven't found one I like yet.

> Has anyone sucessfully run CP/M on a PC without running under dos and/or
> windows?

Well, usualy this doesn't work, because of the different CPUs
(I assume we are talking about CP/M80 - CP/M86 will of course
boot on most classic PCs). The only way beside Emulators under
DOS/Win, and rare coprocessor boards is of course the NEC V20.

A V20 is for all PC/PC-XT machines a must, because of about
10% faster execution (the V20 core is build like the 186/286).

As a nice give away you also get an 8080 CPU for free. There
have been two solutions AFAIR. One was booting MS-DOS and
starting a bootloader for CP/M80 (a), the other was a CP/M
disguise for MS-DOS (b).

The Bootloader programm loaded an 8080 BIOS which supported
hard MS-DOS Hard disks into memory, did setup the memory
tables for the 8080 and switched into 8080 mode to boot CP/M
from HD. There where several problems regarding disk storage,
so the system worked only reliable from floppy disks. I heared
also about a Version which booted from almost ordinary CP/M
floppies. All switching code fitted into the PC boot sector.
I never had this version, and I didn't play a lot with the
hard disk version, but I used the other programm (b) for
several years.

You could start CP/M programms right from the MS-DOS command
line, or switch into CP/M command line. The Programm itself
replaced CP/M and redirected all CP/M functions to MS-DOS
functions - thanks to the similarities :) There where even
'utilities' to switch DOS pathes wihile in CP/M, etc. pp.
The performance was quite acceptable (faster than a 8080 at
5 MHz), and you could use almost all PC Hardware.

I used this programm to run CP/M applications for several
years under MS-DOS - I never had the time to redo them for
the PC. I even kept the XT some time as CP/M machine when
I already had an 386. The machine was also equipped with a
screamer add on board, so the CPU was running most of the
time at 8 MHz.


VCF Europa 3.0 am 27./28. April 2002 in Muenchen
Received on Tue Apr 09 2002 - 14:09:48 BST

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