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From: jp@lanl.ARPA (James Potter)
Newsgroups: net.micro.cpm
Subject: Re: Directory
Message-ID: <861@lanl.ARPA>
Date: Sun, 23-Mar-86 21:43:55 EST
Article-I.D.: lanl.861
Posted: Sun Mar 23 21:43:55 1986
Date-Received: Tue, 25-Mar-86 05:05:45 EST
References: <2017@brl-smoke.ARPA>
Reply-To: jp@a.UUCP (James Potter)
Organization: Los Alamos National Laboratory
Lines: 25



I am running Concurrent CP/M.  The time/date stamping is optional and
uses 25% of the directory for the date and time info.  What you have to do
to partition your disk is to set up drive definition entries for each
partitiion.  One of the pieces of information in each table is how many
tracks to offset for the start of the "logical disk".  Perhaps you
remember for the floppy disks there are two tracks reserved for the system.
This uses the same entry to the table that I am describing for the 
partitioned hard disk.  There is no limit on the number of traks to
skip.  For instance if your disk has 315 tracks (cylinders), skip 0
for partition A, 105 for partition B, and 210 for partition C.  If there
are 6 heads and 9 1K sectors per track this divides the disk into three
5.6 Megabyte partitions.  There is no special reason why each partition
needs to be the same size.  Dividde it up however you like.  All of this
requires that you modify your BIOS and reassemble it.  You cannot do this
without the source code for at least this part of your BIOS.  Consult your
computer manuals.  I have set up my CompuPro system with an 8 Mbyte hard
disk as drive A and a 16 Mbyte hard disk with two 5 Mbyte and one 6 Mbyte
partitions.  It took me a while to figure all of the ins and outs of this,
especially having two different hard disks with differing partion schemes
but it is basically straight forward once you learn all the details you
would rather not have learned about your system.

Jim Potter  jp@lanl.arpa