Re: Sider (Xebec/Datamac SASI) drive and UCSD Pascal 1.1 (Apple Pascal)

[msg <msg@REMOVETHIScybertheque.org>]

Thanks much John for your reply; you've shown me the path.

I apologize for failing to study Barry's paper more carefully;
I was distracted by the cold-boot issue and this reference in
his paper diverted my attention:

  Since these drivers are configured
  into the system after the operating system starts to run, this method
  will not work for configuring drivers for devices that the system
  must cold boot from.  Some of supporting code in the RSP, boot and
  Bios may make the task of bringing up boot drivers easier though.

> > If one could change the assignment of the root volume after
> > booting from floppy, from #4 to (say) #9, and then write the
> > boot area, the cold boot process should work.
> 
> This is how ATTACH itself works. It manipulates entries in a
> user driver jump vector table, pointed to by $E8/E9. In 1.1,
> this points to $FE80, and maps to the last block of
> SYSTEM.APPLE.  This table is followed by the unit table at
> $FEB0. Presumably Xebec is patching the table on disk to mount
> selected volumes at boot time.

It appears that I should try to generate an ATTACH.DATA which
specifies units 4,5,11, and 12 and boot with this as the next
experiment.

The existing ATTACH.DATA contents:

0000    4d 53 43 39 37 30 30 20  00 00 00 00 30 1e 00 00   MSC9700
....0...
0010    00 a0

I have ATTACHUD.CODE but not the source so deciphering the above
would probably require creating some ATTACH.DATA examples with
various values and examining the differences for clues.  In the
alternative, if you don't mind us getting a disk image of that
ATTACH: volume with SHOWAD.CODE, things would go a bit faster.

The driver name is obviously MSC9700.

> 
> The volume named ATTACH: has a utility named ATTACHUD.CODE to
> create new ATTACH.DATA files, and I see a utility named
> SHOWAD.CODE that looks like it might list the contents of your
> existing ATTACH.DATA file.
> 

Fortunately, the cold boot process involves loading a snapshot
of the last running system (which will contain the bound drivers)
and the attach process at that point is not needed.

The program XBOOT.COM.CODE writes the boot area; if the running
system doesn't reference the floppy for the root vol. the booted
system won't either.

Regards,

Michael