CP/M CBIOS question

From: J.C. Wren <jcwren_at_jcwren.com>
Date: Fri Nov 21 01:19:28 2003

        I'm building a BIOS for a Z80 card to use a 32MB CF disk. I started with the
CBIOSX.MAC from SIMH, since it's all I had on hand, and it's a running
system. When building the DPBs, I have two options. I could create a DPB
for each 8MB slice, adjusting the reserved track count to hide the DPB
entries prior to the current one, or, I could use a single DPB for 8MB, and
do the adjustment in the read/write routines based on the disk number.

        The former method would allow variable sized disk slices, but I can't
particularly thing of a reason I'd want 8MB/6MB/8M kind of arrangement. The
latter method uses few DPBs, but basically causes each slice to be of a
uniform size.

        Can anyone make a good argument for one vs. the other? I'm inclined to
handle it based on the disk number, but if I'm overlooking a good reason for
individual DPBs, I'll switch to that.

        I've generated plenty of CP/M BIOS (many many years ago...), but never built
one for a multiple logical drives on the same media.

        --jc
Received on Fri Nov 21 2003 - 01:19:28 GMT