Question for BDOS guru

Question for BDOS guru

Post by Jon Aldri » Thu, 02 Aug 1990 22:40:00

Any DRI people reading this, or any BDOS gurus, out there?
I have a specific question about my flavor of BDOS.  I'm
running cp/m-68k on an hp series 200 machine.  The system
documentation specifies support for an HP9133A hard drive.
I have access to an HP9133H.  Can my BDOS be modified to
support this later model (more bytes) disc drive?

I've tried partitioning the 'H' into smaller units comparable
to the 'A' but I get solid disc errors when I try to use it.

Anyone have any clues?

                        Jon "cp/m neophyte" Aldrich


Question for BDOS guru

Post by Jon Aldri » Thu, 02 Aug 1990 17:41:00

It has been pointed out to me that what I really need to do is modify
BIOS instead of BDOS . . . silly me :-o).  So any cp/m-68k BIOS gurus
out there?
                        jon "neophyte+" aldrich


1. BDOS Guru for CP/M-68K

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).


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