GX4000/ASIC CRTC state at reset time.

[arnoldemu]

It appears from initial testing that all CRTC registers are reset to 0, which puts it inline with other CRTCs.

This means the initial display will be black - i.e. no sync. CPC Interrupts do not appear to be active. I think there is no hsync/vsync generated, so no interrupts are happening, but I need to confirm that.

If you then set register 0 to 63 you see border colour and interrupts will be active. Now setting reg 4 shows a short screen because r9 is 0 too.

So, make sure you initialise CRTC values with your cartridge game or you will not get any display.