BDOS Guru for CP/M-68K

BDOS Guru for CP/M-68K

Post by Margaret H. Kn » Thu, 02 Aug 1990 03:21:00

Jon,  you are looking for the right thing, in the wrong place.

The tables that (SHOULD) control the disk size and configuration
are the DPH (disk parameter header) and DPB (disk parameter block).
They are located in the BIOS, which is unique to each machine type
you are using.  The BDOS and CCP doesn't change from machine to
machine (at least, not for a particular version of CP/M-68K).

You can get SOME idea of the DPH and DPB from the DSK: display of
the STAT command.  To really look at the tables you need to do
the following:

        Bring up DDT

        Punch in a little program to do a SELECT DISK

                BIOS function 9

        The value returned in Reg. D0.L is a pointer to
                the DPH.  Eight words into the DPH is a
                pointer to the DPB.  Pretty much everything
                the system knows about your disk is
                contained in these two tables.

If you have source to the BIOS, modifying it for a bigger disk
(or partitioning it) is trivial.  If not, it can be a challenge.
One problem is that the CSV and ALV may need to be increased
in size for a bigger disk.

For further information, check pages 24 and 40-45 of the
CP/M-68K SYSTEM manual (note: page numbers may vary, I am
looking in an old manual).



1. CP/M, MP/M, CP/M-86, CP/M-68K source; binaries; apps

This is actualy It is my site, and it has been
on-line for abiout 9 weeks now.


And you never will. I have been specificly prohibited from posting
anything in the  "Concurrent" family of products. Caldera has sold
them to someone else, and doesn't own them anymore. Therefore, they
can't grant me the rights to distribute them.

Tim Olmstead
webmaster of the CP/M Unofficial web page

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