| Address | Read register | Write register |
| ^40 | unused | DMACTL |
| ^41 | unused | CHRCTL |
| ^42 | unused | DLPTRL |
| ^43 | unused | DLPTRH |
| ^44 | unused | HSCROL |
| ^45 | unused | VSCROL |
| ^46 | unused | unused |
| ^47 | unused | PMBASE |
| ^48 | unused | unused |
| ^49 | unused | CHBASE |
| ^4A | unused | WSYNC |
| ^4B | VCOUNT | unused |
| ^4C | LPENH | unused |
| ^4D | LPENV | unused |
| ^4E | unused | NMIEN |
| ^4F | NMIST | unused |
CHRCTL
- Characters control
DLPTRL DLPTRH
- Display List pointer
DMACTL
- DMA control
HSCROL
- Horizontal scroll
LPENH
- Light pen horizontal position
LPENV
- Light pen vertical position
NMIEN
- NMI enable
NMIST
- NMI status
PMBASE
- Player/missile base
VCOUNT
- Vertical count
bit 0 - display characters 128-255 as spaces
bit 1 - display characters 128-255 as inverse
bit 2 - display all characters upside down
bits 1,0 - width of screen
00 - screen off
01 - narrow screen - 256 pixels
10 - normal screen - 320 pixels
11 - wide screen - 384 pixels
bits 3,2 - DMA for Players/Missiles
00 - no DMA for P/MG
01 - DMA for missiles
10 - DMA for players and missiles
11 - DMA for players and missiles
bit 4 - P/MG resolution
0 - 120 lines
1 - 240 lines
bit 5 - DMA for Display List
bits 7-6 - unused
bits 5-0 - unused
bit 6 - enable VBLKI
bit 7 - enable DLI
bits 5-0 - unused
bit 6 - VBLKI occured
bit 7 - DLI occured
High byte of P/MG data
Contains number of scanline divided by 2.