Expansion Bus Enable Register
From SpecNext official Wiki
| Number | $80 |
|---|---|
| Readable | Yes |
| Writable | Yes |
| Short Description | Expansion bus enable/config |
| Bit | Description |
|---|---|
| Values affecting machine immediately | |
| 7 | 1 to enable Expansion Bus |
| 6 | (since core 3.1.3) 1 to enable romcs rom replacement from divmmc banks 14/15 |
| 5 | 1 to disable I/O cycles and ignore IORQULA |
| 4 | 1 to disable memory cycles and ignore ROMCS |
| After soft reset (will be copied to bits 7-4) | |
| 3 | 1 to enable Expansion Bus |
| 2 | (since core 3.1.3) 1 to enable romcs rom replacement from divmmc banks 14/15 |
| 1 | 1 to disable I/O cycles and ignore IORQULA |
| 0 | 1 to disable memory cycles and ignore ROMCS |
Set to 0 upon hard reset.
(new register since core 3.0.5)
(note: Next registers with number higher than $7F are inaccessible from Copper code)