Re: Making a bootable Pascal RAM disk

[david@wraith.cs.uow.edu.au (David E A Wilson)]

> Msg #7359 in *Apple II* Created on 05/05/93 at 19:23:45
> To: ALL, From: DON MELTON
> Subject: Apple ][+ UCSD Pascal Boot Unit(#4)
> 
> I'm trying to design a non-volatile RAM-Disk for an Apple ][+ which will
> allow me to boot UCSD Pascal 1.2.  I can find information on how to
> build a block structured device driver, but all the references I have
> neglect to discuss the intricacies of making the device a bootable
> device.  Does anyone know what's required to do this or where to go to
> find out?

I personally would upgrade to Apple Pascal 1.3 before trying this. It has
the ability to boot from ProDOS block devices & smartport devices in slots
4, 5 & 6. To make the device bootable you would use the format program that
comes with Pascal 1.3. This installs the needed boot block as well as
building the initial directory (and physically formatting the media if
needed - not for RAM disks). Pascal 1.3 had no problem recognising my
home made ROMdisk card (until I moved it to slot 7) even though it only
had ProDOS file systems on it - it reported the correct size (and that
it was not a Pascal disk).

There are at least two boot blocks used by Pascal 1.3. The first is used
on Disk ][ 5.25" drives and the second on block devices like Hard drives
and 800k 3.5" floppies. I ran into this when I tried to install 1.3 on my
hard disk from my 5.25" drive connected to a UDC. This makes the floppy
into a smartport drive and the boot blocks on the distribution 5.25" disks
did not work.

ProDOS has a smarter boot block that checks to see if the device you booted
from is a Disk ][ or a block device and jumps to different code.
-- 
David Wilson				+61 42 213802 voice, +61 42 213262 fax
Dept Comp Sci, Uni of Wollongong	david@cs.uow.edu.au