29 Jan
2009
29 Jan
'09
3:24 a.m.
Tony Duell wrote:
Hmmm... Some of the Radio Shack software packages
included disks for both
machines, but he programs on them were not quite the same (they were
probably uilt from the same sourve with a few conditionals, but they
weren't the same binaries). And I have a couple of such packages that are
Model 3 only.
That's a good point. Radio Shack continued to target their Model III
software for TRSDOS 1.3. In addition to its unique disk format, TRSDOS
1.3 made a number of changes to the function calls (expanding FCB's from
32 to 50 bytes, for example). Fortunately, the other Model III operating
systems ignored most of the weirder differences.
But it was fairly easy to write a program that worked on both the Model
I and III (having written a number of such programs myself). Only a few
of the commonly used addresses were different, and a small routine could
take care of them. There were some programs that were Model III only,
but most also supported the Model I as that market was too large to ignore.
--
Matthew Reed
http://www.trs-80.org
mkr at trs-80.org