Re: FDHD Blues

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

In article <m0nmHg8-00003LC@crash.cts.com> beta@gnh-cathouse.cts.com (Scott Sidley) writes:
> Various info and gak on the SupreDrive controller --- deleted to get rid of
> it.

Speaking of gak:
 
> The SCSI  roms on the scsi cards have 16 banks, 8 for the //e and 8 for the
> GS, it would have been no problem for them to relink to the /ram5 driver in
> the roms... how ever ROM1's (the 80 % rank) dont allow access to 16 bit code
> and slots at the same time.

If the ROM 01 doesn't allow slots to use 16-bit code, how do you think
the built-in SmartPort firmware works?  It starts in emulation mode,
then hops straight into native mode to do its work.

The SCSI card's ROM isn't split between "IIgs" and "IIe" versions.
The same code is used for both (the IIgs has the option of using the
extended SmartPort calls, which just pass a different set of
parameters into the same routines).  If you're using GS/OS, the SCSI
Manager talks directly to the hardware - the ROM is only used prior to
the drivers being loaded from disk.

The majority of the code in the SuperDrive card's ROM is probably for
the card's on-board processor.  In addition to doing the disk I/O, it
has to communicate with the Apple, and on the Apple side, an extended
SmartPort interface is also provided.
I haven't disassembled the ROM yet - it is quite likely that the Apple
code simply passes data through to the card's processor to deal with,
so there may only be 2k of ROM on the Apple side, and 30k for the
card's processor.

Despite all that, I doubt that the ROM would be completely full, and
it would have been nice if Apple allowed the SuperDrive to hook in to
the IIgs's SmartPort.
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz    <--- Note my new E-Mail address!            
Snail mail: P.O. Box 27-103, Wellington, New Zealand