| Bits | Description |
|---|---|
| 7 | 1 to enable the expansion bus |
| 6 | 1 to enable romcs rom replacement from divmmc banks 14/15 |
| 5 | 1 to disable i/o cycles & ignore iorqula |
| 4 | 1 to disable memory cycles & ignore romcs |
| 3 | 1 to enable the expansion bus |
| 2 | 1 to enable romcs rom replacement from divmmc banks 14/15 |
| 1 | 1 to disable i/o cycles & ignore iorqula |
| 0 | 1 to disable memory cycles & ignore romcs |
IMMEDIATE AFTER SOFT RESET (copied into bits 7-4)