[Coco] ML Disk I/O examples?

[Joel Ewy]

Mark McDougall wrote:
> Hi,
>
> Can anyone please point me to some "nice" examples of assembler disk I/O?
> I simply need to open a series of (binary) files and read then into
> memory.
> Target is Coco 3.
>
> The only examples I've seen are from the "Portal-9 Source Pack" and
> there's scarcely a comment in the entire collection of listings!
> Pac-dude is using DSKCON and it makes my head hurt.
>
> Surely there's _commented_ examples around that use disk basic ROM
> routines to open and read files??? Or is it really that painful on the
> Coco?
>
> TIA
> Regards,
>
While it doesn't quite rise to the level of "nice examples", the "Color
Computer Disk System Owner's Manual and Programming Guide" has has a
section on "Technical Information" in chapter 11, including an
explanation of the File Allocation Table and how to use the DSKCON
routine in machine language programs (page 60).  It does give a couple
very brief commented examples on page 61.  You can download this manual
from www.trs-80.com (
http://www.trs-80.com/cgi-bin/down-manual-hw.pl?Color_Computer_Disk_System_Owners_Manual_(1981)(Tandy).zip
).

Granted, my 6809 assembly language is about like my German or Koine
Greek -- I can read a little, but don't write much without great
difficulty and much consultation of the books -- but it looks to me as
if this shouldn't be too difficult, and the Rad Shak manual has most of
the information you would need.  The hardest part is that you apparently
need to read and process the directory yourself.  You give DSKCON the
sector number that you want to read or write and the address of a sector
buffer and it does it.  That's about all you get.  Maybe the Unravelled
series reveals an undocumented routine to process the directory.

JCE