Need information on TRSDOS 1.3 internals - test-drb@ccmp.vtda.org

7 Dec 2002

...
  > I think you want _TRS-80 Disk and Other
Mysteries_.  That was one of
 > the Mysteries books I didn't have, but ISTR that Al turned up a copy
 > recently. 
On Fri, 6 Dec 2002, Tim Mann wrote:
...
  No, that only covers Model I TRSDOS 2.x and NEWDOS
2.1.  Sellam asked
 about TRSDOS 1.3, which I have to assume means Model III TRSDOS. 
Fred Cisin wrote:
...
  True.
 But before we deal with the parameters (MOSTLY minor) that differ, he
 needs a tutorial on how the directory structure works for that family
 of operating systems.  Pennington's book provides a good one, unless 
 and until one of us has an opportunity to sit down with him and go 
 through the details. 
Granted, Pennington's book is a good place to start, even though it
doesn't cover the differences in Model III TRSDOS.  It doesn't help
Sellam much, though, if he doesn't have a copy.

In my other reply, I gave a pointer to the on-line Programmer's Guide to
TRSDOS/LS-DOS Version 6.  Here it is again:
http://www.tim-mann.org/trs80/doc/prgguide.pdf  Although the Guide is
denser and not nearly as fun to read as Pennington's book, it contains
the same information (and more) and has the advantage of already being
on-line.  It also has the same drawback, namely that it doesn't cover
the differences in Model III TRSDOS.

...
  For example, for READING files, he doesn't need to
know all of the 
 details of the H.I.T., but I'm sure that he would appreciate learning 
 it ANYWAY, and he will need it sometime in the future when he wants 
 to WRITE files. 
Does Model III TRSDOS compute the HIT codes the same way as the other
TRSDOS-like systems?  I don't recall.  Since Radio Shack randomly
changed so many other things (sectors starting at 1 instead of 0, not
having directory entries for the system files, swapping the DAMs,
changing directory entries from 32 to 48 bytes, various smaller
details), it wouldn't be surprising.

-- 
Tim Mann  tim(a)tim-mann.org  http://www.tim-mann.org/