Changes
/* Interrupt management */
Interrupts on the CPC are created by the Gate Array based on settings from the CRTC. The Gate Array has an internal counter R52 (the R is for Raster) that counts from 0 to 51, incrementing after each HSYNC signal.
On all CRTCs, interrupts always start 1µs after the end of an HSYNC. But on CRTCs 3/4, HSYNCs occur 1µs later than on CRTCs 0/1/2. Which means that on CRTCs 3/4, interrupts start 1µs later too than on CRTCs 0/1/2.
R52 will return to 0 and the Gate Array will send an interrupt request on any of these conditions:
