> the C116 prototype shown there doesn't have the PLA and therefore has no > decoding logic for any I/O-devices (it also lacks the banking logic). So > the only built in I/O was the port in the CPU which had to handle > everything. Yes, I had forgotten that. > As you pointed out, using P7 would disrupt the IEC bus if you pressed > PLAY on the datasette during data transfer. I assume that's the reason > it was changed later when the PLA was added. I don't have a ROM listing > of the 264 ROMs, but I'd be surprised if the -04 and -05 KERNAL-ROMs > would still be able to use CPU-P7 for the tape sense. Having tested it on a +4 where I moved the jumper to J9, the cassette does not then work on an -05 kernal. I have a huge excel spreadsheet with *all* the known kernal ROMS dumped into it. It's all in hex and not a dissassembly but it does highlight the differences between adjacent ROM's. If I look at the differences between 05 and 01, I am not even sure the 01 kernal supported it, the differences do not seem to related to handling $01. I seems peculiar that the +4 board is the only board to have the jumpers when it was one of the later evolutions from the original 9-IC TED. Rob Message was sent through the cbm-hackers mailing listReceived on 2012-01-25 15:00:39
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