All the following processor timings are based on a bog
standard 8MHz 68000 as found in all standard ST's.

Clock cycles per line (50Hz)      : 512
NOPs per scan line (50Hz)         : 128
Scan lines per VBL (50Hz)         : 313

Clock cycles per line (60Hz)      : 508
NOPs per scan line (60Hz)         : 127
Scan lines per VBL (60Hz)         : 315

Clock cycles per VBL              : 160256
NOPs per VBL                      : 40064

Pixels per clock cycle (low res)  : 1
Pixels per clock cycle (med res)  : 2
Pixels per clock cycle (high res) : 4
Pixels per NOP (low res)          : 4
Pixels per NOP (med res)          : 8
Pixels per NOP (high res)         : 16