10 Apr
2002
10 Apr
'02
2:56 p.m.
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
lgwalker(a)mts.net
bigwalk_ca(a)yahoo.com
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/