Code: Select all
138 670 x 2
-----v----- ----------
CPU R/W-|A0 VCC| CPU A12-|WA RA|-CPU A14
CPU A0-|A1 /Y0| CPU A13-|WB RB|-CPU A13 ++++++++-VCC
CPU A1-|A2 /Y1| | | ||||||||
/ROMSEL-|/E1 /Y2| ---------------|/WE /OE|------ RRRRRRRR
CPU A14-|/E2 /Y3| | | | | ||||||||
M2-|E3 /Y4|---- CPU D0-|D0 Q0|-----|----|||||||+-PRG A13
|/Y7 /Y5| CPU D1-|D1 Q1|-----|----||||||+--PRG A14
|GND /Y6| CPU D2-|D2 Q2|-----|----|||||+---PRG A15
----------- CPU D3-|D3 Q3|-----|----||||+----PRG A16
00 ---------- | ||||
-----v----- CPU D4-|D0 Q0|-----|----|||+-----PRG A17
CPU R/W-|1A VCC| CPU D5-|D1 Q1|-----|----||+------PRG A18
CPU R/W-|1B 3A|-CPU A13 CPU D6-|D2 Q2|-----|----|+-------PRG A19
PRG /OE-|1Y 3B|-CPU A14 CPU D7-|D3 Q3|-----|----+--------PRG A20
|2A 3Y|-+ ---------- |
|2B 4A|-+ |
|2Y 4B|-+ |
|GND 4Y|----------------------------------
-----------
But it does not work as I expected. The fixed bank worked perfectly, but writing to any regs didn't switch any bank.
Oh, one thing is unusual: the two 670s are a little hotter than 138 and 00. Not burning hot, but noticable. Maybe short-cut somewhere?
Could anybody give me some hints? Thanks!