VDP Color Registers
This page was last modified 02:14, 6 December 2016 by Mars2000you.

WIP

Contents

Control Register 7

This control register is common to all MSX generations and can be read/written with the MSX-BASIC instruction VDP(), using the value 7.

Bits Code Meaning
7 to 4 TC3 to TC0 Text color in screen 0
3 to 0 BD3 to BD0 Background color in screen 0, border color in screens 1 to 5, 7 and 10
4 to 0 BD4 to BD0 Border color(s) in screen 6
If bit 4 set to 0, only bits 1 and 0 define border color
If bit 4 set to 1, bits 3 and 2 = color for even pixels, bits 1 and 0 = color for odd pixels
7 to 0 BD7 to BD0 Border color in screens 8, 11 and 12


Control Register 12

This control register is available on the MSX2/2+ VDP and can be read/written with the MSX-BASIC instruction VDP(), using the value 13.

This register is only for SCREEN 0 width 41-80. If attributes for blinking are set, color set in this register and color set in Control Register 7 are displayed alternatively (blinked).

Bits Code Meaning
7 to 4 T23 to T20 Text blink color in SCREEN 0 width 41-80
3 to 0 BC3 to BC0 Background blink color in SCREEN 0 width 41-80


Control Register 13

This control register is available on the MSX2/2+ VDP and can be read/written with the MSX-BASIC instruction VDP(), using the value 14.

This register is used for SCREEN 0 width 41-80 and all the Bitmap screens (SCREEN 5 to 8, 10 to 12). Two pages can be alternatively displayed (blinked). You need to write to this register in order for blinking to start.

Bits Code Meaning
7 to 4 ON3 to ON0 Display time for even page
3 to 0 OF3 to OF0 Display time for odd page


Control Registers 20, 21 and 22

These control registers are available on the MSX2/2+ VDP and can be read/written with the MSX-BASIC instruction VDP(), using the values 21 to 23. These registers specify the Color Burst frequency of the composite video.

The following values are preset on power-on:

Register Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
20 0 0 0 0 0 0 0 0
21 0 0 1 1 1 0 1 1
22 0 0 0 0 0 1 0 1


It is not recommended to change these values. If all the bits of these registers are set to 0, color burst of the composite video is not performed. If values are returned to above values, the VDP will start generating normal color burst signal.

Note that many MSX2 and higher computers don't use these registers because they produce the composite video from the RGB signal.