AndrewP wrote:
Yup, very nicely condensed. Interestingly I hadn't realised the X16 would just work with a 65C816; I'm guessing it must just ignore the bank address and still use the X16's bank switching.
Yes, it allows taking advantage of the '816 benefits available in what in DOS used to be called a "small" memory model.
AFAIU, all that was required to make the socket '816 compatible was to provide a pull-up resister for Pin3, which is an /ABORT input pin in the 65816 and a legacy Phi0 output on the 65C02, so that it doesn't float low when the 65816 is swapped in.
Evidently a recent modification has been done to the Vera processor to allow faster moves of data between system memory and the memory internal to Vera, by allowing Data ports 0 and 1 to be written in consecutive clock cycles, so that 16bit data mode can be used for the copy.