Background: My son and I both acquired Kaypro IIs, and no way to write new disks. If I had an older DOS machine it would be simple, but eBay sellers want gold for old machines nowadays. So I found a IBM-labelled MPI DS DD 5.25" drive. Now I just need a way to read and write disks. And, if the C1541 could do it with a CPU and VIA, I should certainly be able to do it with a MCU with ports. Yes, I know that this has already been done both with the Arduino and Raspberry Pi, along with many other projects. But if I wanted a simple way to do it, I wouldn't own a 265SXB, would I?
Finally, to the question! From the memory map, I can see what looks like a CIA split across 00:DF00-00:DF07 and 00:DF20-00:DF27, which should give me 8 ports to bit-bang with. Unfortunately, this isn't enough for all of the signals I need to send or read from the floppy controller. I do see a parallel interface at 00:DF78-00:DF7F that might be able to be used, but I've got no information on how these ports might work or if I could use them in this way. I see that they can manage interrupts, which I won't need to use.
Has someone teased out all of the available ports from these chips? Documentation, as has been said many times before, is really terrible...
