FD-2000 and CMD Native Partition Info

From: eyethian (eyethian_at_msn.com)
Date: 2001-11-16 06:50:42


Thanks to Professor Dredd for posting some technical information about the
CMD's Native partition layout. It can be found at:


And look for the CMD Native article.

However, there are some additions; Track 1, Sector 0 is reserved for the CBM
boot sector. This holds true even for CMD Native partitions. Insert special
bootsector code there at Track 1, Sector 0, say at the CMD HD located at
unit 10, issuing the BOOTONU10 command from 128's direct mode will then
initiate the boot sequence.

Secondly, the BAM entries located at Track 1, Sectors 3-33 should be
constant, regardless of the CMD partition size. In the case of the FD-2000,
a lot of sectors in the BAM would be unused, but they should be reserved and
not used by CMD DOS in writing actual disk data. I guess this is due to
compatibility as CMD FD DOS is based on CMD HD DOS and not a lot of code has
changed in this respect.


After some preliminary disassembly of FD-TOOLS program, I ascertained that
the default partition number is located at offset $e2 & $e3 located in the
Hardware Block of the system partition of a FD-2000 formatted diskette. It
is not a word value, but a value representing the default partition is
stored twice. For example, if partition #2 was set the default partition,
offset $e2 and $e3 would contain a value of 2 each. Anyway, I will confirm
this when I do make some test FD-2000 disks and use 1581COPY to load them
into my PC and use HIEW.

-Todd Elliott

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