[comp.sys.mac.system] ROM totally patchable? APB for Disipline? 2 ext floppies?

vthrc@brolga.cc.uq.oz.au (Danny Thomas) (04/15/91)

Hi netland,
           
The first question about how completely the ROM can be patched is to 
answer why some upgrades won't work with certain older ROM generations, eg 
the 64K and 128K eras. The boot code obviously can't be patched, and a 
complete patch might be required to make a 32bit-clean system. I think a 
short explanation might be of interest to other people although it is 
probably obvious to any self-respecting hacker.
    TN96 describes some SCSI bugs in the boot part of the ROM and TN176 
describes a bug in the original MacII ROMs that causes a crash when 4M 
SIMMs are installed. The only ROM upgrade offered for the II also requires 
a FDHD drive. Both of these are happening during boot.

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Does anyone know what happened to Discipline? This was a debugging utility that did a sanity check on each call to the toolbox. It is something I've been 
meaning to get for a long time, but it seems to have disappeared from 
APDA's catalog - at least it isn't in my issues of APDAlog.

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And finally why can't you run 2 external floppies, from a Mac+ in this 
case?
The Apple 3.5 Floppy Manual says "You cannot install a second external 
800K drive on a Macintosh. Although it is physically possible to connect 
one, a second external drive won't work." Apparently you can run an 
unlimited number with a IIGS so it must be something in the Mac hardware 
or software. We have a person who'd like to do this, he doesn't what the 
noise that would come from a hard disk.

Danny Thomas     email: vthrc@brolga.cc.uq.oz.au
University of Queensland.