Re: Creating Apple /// boot disks using MacADT

[dempson@actrix.gen.nz (David Empson)]

jjj <jjj.@.i.o.com> wrote:

> On 2008-01-19 02:17:36 -0800, "Michael J. Mahon" <mjmahon@aol.com> said:
> 
> > It's easy enough to look at block 1 and be sure...
> > 
> > There are lots of slips possible when Apple II tools are used
> > to capture/transmit Apple /// disks, since you can be pretty
> > sure that the images have not been verified to boot SOS since
> > originally being archived.
> 
> OK I looked at Block $0001 on the Apple /// System Utils disk. It was
> just full of zeroes.

That's not going to boot an Apple ///.

> However, Block $0000 is exactly the same as Block $0001 of the ProDOS
> disk.

Was that a type? I'd expect block 0 of a SOS disk to be the same as
block 0 of a ProDOS disk.

SOS doesn't use block 0 and ProDOS doesn't use block 1.

A "dual boot" disk will have the ProDOS boot code in block 0, and the
SOS boot code in block 1.

A ProDOS-only boot disk will have ProDOS boot code in block 0 and
probably zeros in block 1.

A SOS-only boot disk will have SOS boot code in block 1 and probably
zeros in block 0.

A disk which isn't set up to boot either OS (formatted and has a
directory, but no boot blocks) could have arbitrary junk in both blocks
0 and 1.

> So, I copied Block $0000 of the Apple /// disk into Block $0001 of the
> Apple /// disk, but I still get the IO ERROR.
> 
> Then I tried this: I copied Block $0000 and $0001 exactly from the 
> ProDOS disk to the Apple /// disk. Still, IO ERROR.
> 
> If I try to boot the Apple /// from the ProDOS disk, it gives a 
> different error: SOS KERNEL NOT FOUND.

This implies that ProDOS disk contains the Apple /// boot code in block
1. It attempts to load a file called SOS.KERNEL (or something like
that).

Not sure what is going on with the I/O ERROR messages, but that usually
means the disk is unreadable, or it tried to access a nonexistent block
(block number out of range).

Perhaps there is a problem at a later point on the Apple /// disk.

> The weirdest thing is that in Block $0000 of the ProDOS disk, line 010
> says the first part of my e-mail address: "JJJ.@.I" What the hell?! How
> could my e-mail address be in there?

What do you mean by "line 010"? What address offset? What are the actual
byte values at that point? (ASCII is ambiguous - might have the high bit
set or clear.)

I don't have a working Apple II system on hand to check if that is
normal.

> I am guessing that somehow my FTP program is messing up the disk 
> images, since why else would part of my email address be in there? Or
> is it just the weirdest coincidence of all time? I'm just using Fetch
> to get these DSK files from asimov.net. But why would it put part of my
> e-mail address but not the whole thing?
> 
> It's only on the ProDOS boot disk. But also I formatted a blank disk 
> with ProDOS and "JJJ.@.I" is also on that one! I'm putting my money on
> crazy coincidence...
> 
> Incidentally I noticed the Kernel file starts in Block 7 on the Apple
> /// System Utils disk.

That's arbitrary.

The directory is blocks 2-5, and the volume bit map is block 6. The
first file saved on the disk will normally start at block 7 but it just
happens to be the SOS Kernel.


-- 
David Empson
dempson@actrix.gen.nz