I have been meaning to pick up a V-20 for my Zenith ZFA-161 for some time
mainly for the speed-up without knowing about the V-20s CPM capabilities.
The luggable 161 has a passive backplane and I always thought you had to
get a CPM card for it. This clarifies things.
It seems you can also use it on a PCjr and DEC Rainbow, and I imagine any
8088 box.
Among my archived stuff I also found a program from a one-man operation
called Micro Computing Assoc. which it appears is now defunct. It has all
the operating codes and specs for the V-20. It describes how it booted in
Native 8088 or CPM Emulation. It would seem fairly trivial to switch modes
from what I could see. Unfortunately my programming capabilities are zilch
except for some assembly I learned in my digital course many moons ago.
Anyone know where this bootloader may be found or willing to take up the
challenge of writing a small boot loader ? I can send you the V-20 specs
program (actually just some sort of viewer program with a data file).
On the Rainbow I saw mention of either an EPROM mod (it's documented
according to www.old-computers.com) or choosing the OS on start-up. I can't
remember the boot-up choice on my 'bow and it's buried right now.
The Zenith has an excellent monitor program. I'm wondering whether that
would also show a system choice if fitted with the V-20.
The
http://www.pcenterprises.com/newbegin.htm upgrade site has info on
the PCjr one.
Lawrence
>
> > 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.
>
> Gruss
> H.
>
> --
> VCF Europa 3.0 am 27./28. April 2002 in Muenchen
> http://www.vcfe.org/
lgwalker_at_mts.net
bigwalk_ca_at_yahoo.com
Received on Wed Apr 10 2002 - 14:56:59 BST