Plus 3 Memory Paging Control: Difference between revisions
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core 3.0 changes |
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Any values written to this port should also be stored in $5B67 if you intend to use any OS routines. | Any values written to this port should also be stored in $5B67 if you intend to use any OS routines. | ||
'''NEW in core 3.0:''' | |||
When exiting +3 special paging mode, the banks 5 and 2 are mapped back at regular place. | |||
Revision as of 21:17, 3 October 2019
| Port Number | $1FFD |
|---|---|
| Decimal | |
| Short desc. | Controls ROM paging and special paging options from the +2a/+3. |
| Bit Mask | %0001 ---- ---- --0- |
| Readable | No |
| Writable | Yes |
| Subsystem | Memory map |
Bit mapped to control paging options.
| Bit | Effect |
|---|---|
| 5-7 | Undocumented, may be used for extra bits of slot 4 bank select (see NextPort:$7FFD) |
| 4 | Printer Port Strobe |
| 3 | Disk motor enable |
| 2 | Normal mode: High bit of ROM selection.
Special mode: High bit of memory configuration number (see Memory map). |
| 1 | Special mode: Low bit of memory configuration number. |
| 0 | Paging mode. 0=Normal, 1=Special. |
Any values written to this port should also be stored in $5B67 if you intend to use any OS routines.
NEW in core 3.0:
When exiting +3 special paging mode, the banks 5 and 2 are mapped back at regular place.