Tried today by making a adapter cable for using dual 4k eprom into one 8k.
The eprom is supposed to be used in a Volvo 760 Turbo 1984-85 in Motronic 012 ECU. Then a switch to choose lower or upper data in the 8k eprom.
Found some info in a forum long time ago that I had saved.
The pinouts is not the same so I took a solder DIL24 socket and attach cables on top of it, then led thoose to an experiment circuit board where I have a ZIF28 socket.
I connected the first 12 adress(a0-a11) cables and all 8 data cables. Then ZIF28-20 to DIL24-18 (what is this?) ZIF28-28 to DIL24-24 (Vcc) ZIF28-1 to DIL24-20 (Vpp) Is this necessary if you only read ? ZIF28-14 to DIL24-12 (gnd) ZIF28-27 to ZIF28-14 (gnd) Why ?? ZIF28-2 to switch alternating to ZIF28-14(gnd) or ZIF28-28 (Vcc)
Then I programmed a 27c64 with 4k, then again with offset 1000. Verifies and ok. If I remove the ofset and read from the eprom the buffer fills up as it should with different data.
Then I connect my adapter to my GQ-3X and choose 27c32b(I think) and tries to read it. No matter how my switch is, there is only FFs read.
It seems my adapter does not work. What could be wrong ? I belive my adapter cable is about half feet long. The cable is a floppy drive cable(flat ribbon type, gray)