ncoplin_at_orbeng.com
Date: 2003-09-23 06:09:07
Hi All,
There have been a number of CPU replacement projects for the Commodore, all
of which seem to be using 74688 chips to decode address $00/01. If using a
CPLD, this means 16 lines are dedicated to the address decode. This seems
like an expensive solution....
Is there anything wrong with using a 1N4148 diodes in a wired-OR config to
detect when all top 15 address lines are zero (that is A1-A15). This one
output can then be feed to a CPLD along with A0 thus saving 14 inputs to the
chip.
The other question is buffer/line drivers. Are 74245 chips needed to drive
the address circuits from the cartridge port.
Regards,
Nick
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