On Thu, 20 Nov 2003, ben franchuk wrote:
>
> Was not a version of DECMATE? ( PDP-8 ) also a CMOS PDP-8/Z80 dual machine?
Well, kind of. The DECmate II (and, I believe, the III; I never used a
III) could accept a coprocessor containing a Z80. The only I/O resources
directly available to the Z80 were registers used to pass messages
between itself and the PDP-8; the PDP-8 did all the I/O.
While I had to give up on the Rainbow because it was not good enough as
either an MS-DOS or a CP/M machine, the DECmate II is one of my all-time
favorite CP/M machines.
I knew the Rainbow was in trouble as an MS-DOS machine when I had to
trade my newer version of Turbo C for a friend's older version because
the *command line* version of the compiler had too many dependencies on
the IBM PC ROM BIOS. It was all down hill from there.
As a CP/M machine, I had to give up on it primarily because the Z-80
didn't support the I/O byte. At the time, the sort of dorking around I
was doing with CP/M involved serial communications of some sort; playing
about with serial mice, drawing things on a Tek 4010, communicating
with the VAX on which I did serious work, etc. All of these were done by
fiddling with the I/O byte on all of my CP/M machines *except* the
Rainbow. Consequently, I could write a program and use it on my
Kaypro, Epson Geneva, even the DECmate II; but *not* the Rainbow. I even
had a two-user experimental MP/M setup in which the XIOS sat beneath the
CP/M BIOS using the CP/M BIOS services for all I/O, which included
diddling the I/O byte to perform console I/O for the two users. Didn't
work on the Rainbow.
I never got attached to CP/M-86 because I didn't have development tools
or programming documentation for the system. In fact, my primary method
of using the Rainbow was to load my CP/M-80 TSR that gave me command
line recall and editing, which meant that from then on I could only run
Z80 programs. Consequently, the Rainbow's deficiencies as a CP/M-80
machine were fatal for me.
Oh yeah. The console I/O on the Rainbow was also slow. Not as bad as the
Pro, but the DECmate II's built-in terminal emulation was peppy.
--
Roger Ivie
rivie_at_ridgenet.net
<input type crash>
Received on Fri Nov 21 2003 - 11:21:10 GMT