Re: ROM 3 Questions

["Mark Cummings" <NOTfigjams@primus.com.au>]

I don't have the luxury of owning two ROM-3's, but mine is the first one you
mentioned. The ROMs are 28pin fitted to a 32pin socket. This also matches
the IIGS Hardware Reference Manual 2nd Edition. I noticed that the circuit
diagram shows only the 28 pin version, but pins are referenced to their
equivalent sockket position on a 32pin socket, rather than the chip pin
number. The screen printing on the ROM-3 motherboard also indicates it will
take a larger ROM as an alternate.

I'd say that second one you have is not normal, but a special, perhaps for
Apple technicians or programmers ? (just a wild guess). Maybe those ROMs are
only used to fault find the system, like checking for faulty DRAMs which
can't be found by running the System Self Test (speaking from a bad
experience).
Also, if you look at the KEGS emulator on the PC using ROM-3 code it also
doesn't have that Visit Monitor or Memory Peeker option.
I could probably guess, but tell us what they do ?

Mark


william strutts <wrstrutts1@home.com> wrote in message
news:yq407.154970$DG1.25631829@news1.rdc1.mi.home.com...
> I have two ROM 3 motherboards.  They are basically identical
> except for the actual ROM's.  The First machine has two ROM's
> marked 341-0748 and 341-0737.  The Control Panel Screen
> for this machine shows the options: Control Panel, Alternate
> Screen Mode.  The second machine has these ROM's marked
> 341-0728 and 341-0748 (this is a different size ROM than the
> other machine, it is four pins shorter than the other Machine). The
> Control Panel Screen shows Control Panel, Alternate Screen
> Mode, Visit Monitor and Memory Peeker.  Is there any difference
> between the ROM routines? Why is there the obvious chip
> size difference between the ROM's?
>
> --
> --
> William R. Strutts - wrstrutts1@home.com - Whatever!
>
> C'est moi!  http://www.facelink.com/wrstrutts
>
> Just hacking away...
>
>