> On 2020-02-07, at 19:48, Francesco Messineo <francesco.messineo_at_gmail.com> wrote: > > Hi all, > I should know this, but I probably totally forgot it: what values are > the Data and DDR registers in a MOS6510 initialized to at power on? I > am quite sure their values aren't altered by a /RES low->high input, > but I can't find anywhere in the datasheet what are the power on > values of those two registers. They can't be random (right?) otherwise > a C64 would not start properly most of the times. Mapping says about D6510 ($00): On power-up, this register is set to 239 ($EF), which indicates that all bits, except for Bit 4 (which senses the cassette switch), are set up for Output. But that's all I recall so far. No authoritative sentence about R6510 ($01) It surely has to boot with KERNAL banked-in so I'd presume that the default is probably all ones (1s) -- SD!Received on 2020-05-30 00:50:42
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