October 27, 1999

I have been following some of the comments on the list server digest about the PC99
disk formats etc. There is a "library" of routines used by all the PC99 "dsk"
utilities that essentially allow things like "read a sector from a TI disk given the
sector number", etc. This was to avoid duplicate code, and to ensure that all the
utils worked the same way. It also has some rigorous testing built in to make sure
we are dealing with a PC99 disk and its format (e.g. DSSD, DSDD), etc.

I have attached a util called dskdata.exe that will extract just the data sectors
from a PC99 .dsk file. The syntax is:

dskdata <PC99 .dsk file> <DOS binary data file> <start sector> <end sector>

Example: dskdata pc99.dsk data.out 0 359

will create a file that is 92.160 bytes long. Similarly 0 719 will dump a DSSD .dsk.

This is currently supplied as unsupported software, with the usual disclaimers that
CaDD has no responsibility for whatever havoc this may or may not wreak on your
system. However, anyone is free to use it if they find it useful in extracting just
the raw data from the "inefficient" PC99 .dsk format. (Note that the "inefficient"
format matches the TI format byte for byte, so we don't feel too guilty about that.
Short of writing a compression routine, it doesn't seem you can get more efficient
than doing what the real thing does.)

Having just the raw sector data may makesit a lot easier to move it around. For
example, if you want sector 3, it is 3 * 256 bytes in from the start of the start of
the file (0 based).

This code was done very quickly, with only minor testing. But, since it uses the
(hopefully) tried and tested lib routines, it should be quite good. If you have any
problems let me know and I will try and look at them.

Regards,
Mike Wright
mjmw@ix.netcom.com
(for CaDD Electronics)