cisin at xenosoft.com
Fri Apr 27 10:11:25 CDT 2018
On Fri, 27 Apr 2018, Bill Gunshannon via cctalk wrote:
> CP/M ran on the Model I and the Model III. CP/M was a very adaptable OS.
CP/M required RAM where the TRS80 Model 1 and 3 had ROM.
An unmodified TRS80 (model 1 or model 3) could not run unmodified CP/M.
FMG? marketed a relocated CP/M for the TRS80. But, moving CP/M to a
different area of memory wasn't a satisfactory solution. It worked, and
was CP/M, but few commercial CP/M programs would work with it, since
they assumed that the TPA (Transient Program Area) would be where it
usually was for CP/M. But, it let me use TRS80 Model 1 to teach beginning
basics of CP/M in my disk operating systems class. (such as creating a
zero length file to restart a program)
Parasitic Engineering (Howard Fullmer (later chief engineer at Morrow)
had a company in Berkeley) marketed a sandwich board for the CPU, and
another for the FDC, that altered the memory map, and also provided for
Omikron in Berkeley made a similar setup.
I had both. Neither were cheap.
Later, in the Model 3 days, there were some more relocations and adapters
for CP/M, such as FEC, Holmes, Hurricane labs, Memory Merchant, Micro
Craft. Was Montezuma Micro (Ron Jones?) for Model 3 or model 4?
> Tandy wasn't the only one who tried to do better. Look at the NEC APC.
> Quad Density Double Sided 8" disks. High density color graphics with 256
> colors. Dismal failure in the market because it wasn't fully "IBM
> The follow-on NEC APC/III was a great big step backwards.
Or DEC Rainbow. Or Sirius/Victor 9000. Tandy wasn't the only one who
thought that a "better" MS-DOS machine would be preferable to a clone.
There were many companies who made MS-DOS machines with various levels of
compatibility, who had 80 track per side (96tpi) drives, such
as Burroughs ET2120, Canon AS100, Rainbow, Eagle, IBM PC/JX, Monroe,
Otrona (although their documentation writers misinterpreted 50h (80) as
50! as discussed here 6 months ago), Siemens, Televideo TS1603, Toshiba
T300, . . .
The Toshiba T300, for example, was reasonably compatible, other than 80
track per side disk format, and they swapped the video memory location
between CGA and MDA. I ran PC-Write on one of them (I patched PC-Write
for the other video memory). Later, I loaned 2 of them to the California
NMRI division of Toshiba for them to read disks. Unfortunately, they
returned them after they were finished.
Grumpy Ol' Fred cisin at xenosoft.com
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