Path: utzoo!mnetor!tmsoft!dptcdc!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!portal!cup.portal.com!JerryK
From: JerryK@cup.portal.com (Jerry E Kindall)
Newsgroups: comp.sys.apple
Subject: Re: ProDOS block 0
Message-ID: <21079@cup.portal.com>
Date: 6 Aug 89 19:09:57 GMT
References: <113300095@uxa.cso.uiuc.edu>
Organization: The Portal System (TM)
Lines: 25

Re: making a disk to put in slot 6, to automatically boot slot 5

There are a couple of tricks to this.  First, make sure that the first
byte of block 0 is a 1.  The actual code begins at relative byte 1 of
block 0.  (The 1 indicates how many sectors, that's right, SECTORS, to
read in.  The disk controller has the capability to read the entire track
into memory, on bootup, but Apple never used the capability for some
reason.)

Next, make sure you deactivate the 5.25" drive's motor with an access to
$C088,X.  (If you're always booting from slot 6 you can just access $C0E8.)
This might not be necessary on the IIgs, but it sure is on the IIc, because
the IIc waits for the 5.25" drive to turn off before it will turn on the 3.5.
(That's because both devices use the same softswitches for different purposes.)

After that, just jump to $C500, the PR#5 entry point.

So the complete code for block 0 should be:

00: 01
01: 2C E8 C0
04: 4C 00 C5

/\    Jerry Kindall      JerryK@cup.portal.com
  \/  Death to COBOL     GEnie: A2.JERRY   ALink: A2 Jerry