Hallo Nicholas, > PS: I have headaches when I think about the recently discovered behaviour of > writes/reads to unconnected bits of adresses 0/1. IIRC, the data direction > bit is connected, but the data port bit itself is not. Hard to emulate with a > 6522 that has both registers in a single chip. I didn't understand some things or am not sure I understood it right. Writing to and reading from the direction register returns all 8 bits right, yes? Writing to and reading from the data register only returns the connected bits right, yes? If so what do the other bits, return a (H)? I also assume that the above only concerns the 7501/8501 as AFAIK the 6510 and 8502 behave right, ie. returning all bits right for all registers. If the above is right, is there any software using this feature? IMHO I don't see any negative point in using a 6522 which does not behave like that. FYI, in 1988 I constructed a board with a 6502, 6526, buffers and glue logic for the C64. Worked fine. But lost the board during a move (?? changing house). Groetjes, Ruud http://home.hccnet.nl/g.baltissen/index.htm - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail email@example.com.
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