Changes
CRTC
,/* HSYNC and VSYNC */
The HSYNC width value is interpreted differently between CRTCs. On CRTCs 0/1, if 0 is programmed no HSYNC is generated. On CRTCs 2/3/4, if 0 is programmed this gives a HSYNC width of 16.
CRTCs 1/2 have a fixed VSYNC width value of 16. VSYNC width can be configured with Register 3 on CRTCs 0/3/4. If 0 is programmed this gives 16 lines of VSYNC.
The bit 0 of port B of the PPI changes to 1 as soon as the VSYNC signal is produced by the CRTC.
