18 Jan
2022
18 Jan
'22
12:01 p.m.
I think it might be easier to modify the 680 prom for the I/O addresses
of the board rather than modify the board to match the ROM.
Especially if the address decoding for the I/O is done in PAL (10L8 for
example).
Some 6800 address decoding was done with 74LS138s.? This had the
potential to be inefficient in terms of memory usage or if the '138s
were cascaded then propagation delay could become an issue.
On 1/18/2022 12:54 PM, Chris Elmquist via cctalk wrote:
I have quite a few Motorola Microsystems Exorciser
boards including this
6800 single board computer for which I am lacking any documentation.
I've seen a brochure in Al's collection on Bitsavers but haven't found
any details that might discuss jumper settings or even better,
a schematic.
Wondering if anyone would have a user manual or other detailed docs for
this board?
M68MM01A2 -- has 6800 CPU, 6875 1.0 MHz clock generator, 6850 ACIA and
MC14411 baud rate clock, (4) EPROM/ROM sockets and (2) 6821 PIA sockets
with the 86-pin Exorciser edge connector.
I'm interested in seeing if I can minimally modify it to have a similar
memory map to the Altair 680 so that the Altair's PROM monitor could
run on it.
Thanks!
Chris