Hi Steve,
Made time to compare the schematics last night. Here are the differences I see:
Old K:
pin 21 of EPROM (CS2) grounded (along with CS1 (pin 20) and VSS (pin 12))
Modifed K:
Pin 21 tied to A12 (J10-5) (presumably trace is cut to isolate from ground)
Old K:
PG1 tied to J10-1
Prog. Page tied to J10-12
PG0 tied to J10-4
RESET tied to J10-18
Modified K:
PG1 tied to J10-1, I10-9, and I10-10
Prog. Page tied to J10-12 and J10-9
PG0 tied to J10-8, I10-4, and I10-5
RESET tied to J10-18 and J10-10
I10-8 tied to J10-4
I10-6 tied to J10-11
So, it looks like there are 2 traces to cut (EPROM pin 21 to gnd, and J10-4
to PG0) and a lot of jumper wires to put in.
Basically, looks like the PG1 signal is now used to select the odd or even
bank, and the PG0 signal is used to set A12 for the extended addressing.
Now the question is that if the board is strapped to accomadate the 2732s,
what will happen if you plug a 2716 in? Presumably the state of A12 shouldn't
matter and the game should work, right? Put another way, what happens if you
plug Star Castle 2716 EPROMs into an Armor Attack cpu board? (Just curious if
I'll have burn up 2732s for RO and SC while I'm working on the all in one
27128 hack)
Ray
