[Coco] "Mini DOS" in early CoCo disk programs...

[Robert Gault]

Rogelio Perea wrote:

> What was the purpose of having a "mini DOS" program loaded in early
> CoCo disk programs? I refer to the program writen by R.G. Kilgus and
> that had to be loaded in software pieces like Disk EDTASM and Disk
> Profile for example...
> 

It provides functionality that did not exist in the standard DOS. 
Personally, I did not care for it and wrote my own disk I/O routines or 
linked into the standard DOS. However, if you want to use the Tandy 
code, you must test for the presence of DOS 1.0 or 1.1 and use the 
correct addresses.

  There is a major drawback to Disk EDTASM using the Kilgus code while 
EDTASM is running. Emulators, for the most part, do not correctly follow 
the Tandy specs for directory entries. As a result, you can have 
problems loading EDTASM source code into EDTASM under emulation. The bug 
is that emulators do not make the 2nd 16 bytes of a directory entry all 
zeros.
  This bug strikes primarily with a newly created .dsk image when PORT 
or a similar utility is used to load the image with files. The second 
sixteen bytes of the directory entries are left as $FF $FF $FF etc. and 
EDTASM will not load any source files from the image.