On Sat, 30 Apr 2011, Tony Duell wrote:
The logic voard of a M4 could accept 128K of RAM. Yes,
you could only
have 64K in the CPU memory map at a time, and AFIAK very little
application software made use of the 'extra' memory. It was commonly used
fo a RAMdisk or print spooler.
Many CP/M machines with 128K used it to be able to expand the TPA from
about 53K up to about 63K.
Model 4P
same as model 4, in a Compaq like luggable case
Same disk format and OS, sure, but there are a few hardware differences.
The main one is that the 4P only existed as a disk system (the plain M4
could exist without disks, running ROM BASIC and using a cassette tape
for storage), and as such it didn't have the BASIC ROMs, only a simnple
bootstrap ROM. There was a file on the TRS-DOS master disk that would
effectively load a ROM image into the bottom part of RAM so as to be able
to run softeware that expected said ROM.
I didn't know about the lack of the BASIC ROMs.
'course, I can always fall back on, "I was only talking about the disk
format"
--
Grumpy Ol' Fred cisin at
xenosoft.com