* Even logical VRAM addresses (logical address bit 0 = 0) map to VRAM0 and use R46 for masking.
* Odd logical VRAM address (logical address bit = 1) map to VRAM1 use R47 for masking.
=== Reset ===
The following has been tested using the "software reset" which is triggered through the control port.
* After rest all registers are reset to 0.
* The elected register (port 4) is set to 0 and port read and write increment is not inhibited.
* If reset is held using the "software reset" then reading or writing to the VRAM data port will cause the CPC to hang. I believe the V9990 is continuously asserting /WAIT but I can't confirm through code.
* Reset will stop any commands in progress and will clear pending interrupts.
* If reset is held: 3,4,7,8,9,10,11,12,13,14 and 15 reads databus, port 1 reads 0, port 5 and 6 read status,
=== Coordinates ===