On Wed, 21 Nov 2018, Geert Uytterhoeven wrote:
The 8520 CIA is almost identical to the 6526 CIA, as used in the C64...
The 6526 CIA datasheet says, "In continuous mode, the timer will count from the latched value to zero, generate and interrupt, reload the latched value and repeat the procedure continuously." This suggests that either 0 or N (the latched value) would result from a read from the counter immediately following an interrupt. Who can say which? Just have to try it. The answer should allow us to avoid the risk of a clocksource that jumps forwards and backwards. --
