Layer 2 Access Port
From SpecNext official Wiki
| Number | $123B |
|---|---|
| Decimal | |
| Short desc. | Enables Layer 2 and controls paging of layer 2 screen into lower memory. |
| Bit Mask | %0001 0010 0011 1011 ?? |
| Readable | Yes |
| Writable | Yes |
| Subsystem | Layer 2 |
| Bit | Description |
|---|---|
| 7-6 | Video RAM bank select (write/read paging) |
| 5-4 | Reserved, write 0 |
| 3 | Use Shadow Layer 2 for paging - Layer 2 RAM Shadow Page Register ($13) |
| 2 | Enable Layer 2 read-only paging |
| 1 | Layer 2 visible - Layer 2 RAM Page Register ($12)
Since core 3.0 this bit has mirror in Display Control 1 Register ($69) |
| 0 | Enable Layer 2 write-only paging |