I never was a hardware guy, only did some very small stuff, but I know want to learn this also.
So I want to know how is the address decoding done on the cartridge port of the tutor (not the expansion port). In the cartridge port the RAM / ROM card from tanam work and you got the rom and also ram at c000.
How they did it because the upper adress lines (a0 and a1 , means a14 and a15) are missing on this port?
I ask tanam and he confirm me that it works.
And what the following in the GAL chip did?
; PYUTA16KRAM.EQN - PYUTA2 RAM&ROM CARTRIDGE
TITLE PYUTA2 RAM&ROM CARTRIDGE
COMPANY PARALLEL COMPUTER INC
CHIP PYUTA2 GAL22V10
NC A2 A1 A0 NC NC NC NC NC NC NC GND
NC CE_n CE2_n SELEXM A14 A13 NC NC NC NC NC VCC
CE_n = A0 * /A1 + A0 * A2 + /A0 * /A1 + /A0 * /A2 + /A1 + /A1 * A2 + /A1*/A2
CE2_n =/A0 * /A1 + /A0 * A2 + A1 * A0 + A1 * A2
SELEXM = /A0 * A1 + /A1 * A0 + /A2 * A0 + /A2 * A1
A14 = A1
A13 = A2
Sorry for so much stupid questions, but maybe someone can explain me.