Semantic search
| Number | Readable | Writable | Description | |
|---|---|---|---|---|
| Sprite port-mirror Attribute 1 (with INC) Register | $76 | false | true | Same as Sprite port-mirror Attribute 1 Register ($36) (write second byte of sprite-attributes), plus increments Sprite port-mirror Index Register ($34) |
| Sprite port-mirror Attribute 2 (with INC) Register | $77 | false | true | Same as Sprite port-mirror Attribute 2 Register ($37) (write third byte of sprite-attributes), plus increments Sprite port-mirror Index Register ($34) |
| Sprite port-mirror Attribute 3 (with INC) Register | $78 | false | true | Same as Sprite port-mirror Attribute 3 Register ($38) (write fourth byte of sprite-attributes), plus increments Sprite port-mirror Index Register ($34) |
| Sprite port-mirror Attribute 4 (with INC) Register | $79 | false | true | The same as Sprite port-mirror Attribute 4 Register ($39) (write fifth byte of sprite-attributes), plus increments Sprite port-mirror Index Register ($34) |
| User Storage 0 Register | $7F | true | true | 8-bit storage for user |
| Expansion Bus Enable Register | $80 | true | true | Expansion bus enable/config |
| Expansion Bus Control Register | $81 | true | true | Expansion bus controls |
| Internal Port Decoding b0-7 Register | $82 | true | true | Enabling internal ports decoding |
| Internal Port Decoding b8-15 Register | $83 | true | true | Enabling internal ports decoding |
| Internal Port Decoding b16-23 Register | $84 | true | true | Enabling internal ports decoding |
| Internal Port Decoding b24-31 Register | $85 | true | true | Enabling internal ports decoding |
| Expansion Bus Decoding b0-7 Register | $86 | true | true | When expansion bus is enabled: Internal ports decoding mask |
| Expansion Bus Decoding b8-15 Register | $87 | true | true | When expansion bus is enabled: Internal ports decoding mask |
| Expansion Bus Decoding b16-23 Register | $88 | true | true | When expansion bus is enabled: Internal ports decoding mask |
| Expansion Bus Decoding b24-31 Register | $89 | true | true | When expansion bus is enabled: Internal ports decoding mask |
| Expansion Bus I/O Propagate Register | $8A | true | true | Monitoring internal I/O or adding external keyboard |
| Alternate ROM | $8C | true | true | Enable alternate ROM or lock 48k ROM |
| Memory Mapping Register | $8E | true | true | Control classic Spectrum memory mapping |
| Pi GPIO Output Enable Register | $90-$93 | true | true | Enables GPIO pins output |
| Pi GPIO Register | $98-$9B | true | true | GPIO pins mapped to Next Register |