Apple ProFILE Help Needed

From: Eric Smith <eric_at_brouhaha.com>
Date: Tue Jun 1 05:52:56 1999

James Willing <jimw_at_agora.rdrop.com> wrote about Apple Profile had drives:
> 5) There is no inherent 'format' command in the ProFile controller logic.
> To enable formatting capability you have to install a special chip
> (according to rumour: a Z-80 with a piggyback EPROM) into a vacant socket
> on the ProFile logic board, power up the unit and issue a special command.

A Zilog Z8 actually. Nothing like a Z-80; similar in concept (but not
compatible with) the Intel 8051. As with most single-chip microcontrollers of
that era, it was available in either masked-ROM, ROMless, or piggyback
packages. Some Profile drives were shipped from the factor with piggyback
packages, even though they were rather expensive, presumably because the
masked-ROM parts weren't yet available.

> There have been stories of people who have opened up their ProFiles and
> found the previously mentioned socket occupied by the magic module, but
> last time I looked in mine I was not one of the fortunate (?) ones...

In the 5M drives I've got, the masked-ROM parts contain the same code as
the EPROM on the piggy-back parts. If there was special firmware needed
for low-level formatting, it's unlikely that it is present.

However, I've been told that the standard firmware can do an LLF if it
is given the correct command by the host.

I've also heard that the drive has to be formatted differently for the Lisa
than for the Apple ][ and ///, due to the 532-byte sector size on the Lisa
vs. the 512-byte size on the ][ and ///. On the Lisa, the extra 20 bytes were
used for tags to assist in scavenging corrupted file systems. This carried
over to the Macintosh floppy disks, but was later abandoned.

Anyhow, there was an Apple Tech Note that said something to the effect that
if a customer wanted to take a Profile that had previously been used on a
Lisa, and use it on an Apple ///, it had to be sent back to Level 1 Service
to be reformatted.

Someday I'll have to disassemble the Z8 code.
Received on Tue Jun 01 1999 - 05:52:56 BST