17-01-2022, 01:49 AM
Hi ChickenMan,
The behavior you get is expected. The emulator correctly decodes the PAK 8 address, whereas the real hardware does not.
The problem is with PIN26 of the the "C" ROM IC15. From memory this pin is held to +5V and doesn't get the decoded signal for the upper bank as the "E,F,G,H & I" ROMs do.
So when you place a 27128 ROM in the ROM C position, due to PIN 26's being hardwired to +5V it selects the upper bank, hence you loose the WORDBEE selection. This is not a problem for the 2764 as that pin is NC.
Not having a MB8328 board myself I am not 100% sure PIN 26 is hardwired to +5V but from my research indicates that it is very likely.
Isolating PIN 26 from the +5V and connecting a jumper from PIN 26 to pin 1 of IC28 will solve your problem.
I can confirm that my modified MB1732 board which I have changed to run as a PC85b works fine with Wordbee in PAK 0 and Typing Tutor in PAK 8 locations.
PS, Very annoying that I can't see the picture of the rom_c.png in your post while logged in, I have to log out to see it. I would be nice to get rid of this software bug.
Ernest
The behavior you get is expected. The emulator correctly decodes the PAK 8 address, whereas the real hardware does not.
The problem is with PIN26 of the the "C" ROM IC15. From memory this pin is held to +5V and doesn't get the decoded signal for the upper bank as the "E,F,G,H & I" ROMs do.
So when you place a 27128 ROM in the ROM C position, due to PIN 26's being hardwired to +5V it selects the upper bank, hence you loose the WORDBEE selection. This is not a problem for the 2764 as that pin is NC.
Not having a MB8328 board myself I am not 100% sure PIN 26 is hardwired to +5V but from my research indicates that it is very likely.
Isolating PIN 26 from the +5V and connecting a jumper from PIN 26 to pin 1 of IC28 will solve your problem.
I can confirm that my modified MB1732 board which I have changed to run as a PC85b works fine with Wordbee in PAK 0 and Typing Tutor in PAK 8 locations.
PS, Very annoying that I can't see the picture of the rom_c.png in your post while logged in, I have to log out to see it. I would be nice to get rid of this software bug.
Ernest