Difference between revisions of "Memory Paging Control"

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Any values written to this port should also be stored at $5B5C if any OS routines are in use.
 
Any values written to this port should also be stored at $5B5C if any OS routines are in use.
 +
 +
{| class="wikitable"
 +
! Bit !! Effect
 +
|-
 +
| 6-7 || Undocumented
 +
|-
 +
| 5 || Lock memory paging (setting to 1 locks pages and cannot be unlocked until next reset)
 +
|-
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| 4 || ROM select (low bit of ROM select on +2/+3)
 +
|-
 +
| 3 || Shadow Screen toggle
 +
|-
 +
| 0-2 || Bank number for slot 4 ($C000)
 +
|}

Revision as of 23:48, 18 August 2017

Number $7FFD
Decimal
Short desc. Selects active RAM, ROM, and displayed screen.
Bit Mask
Readable No
Writable Yes
Subsystem Memory map


Selects the active memory page in slot 4 at $C000. See Memory map.

Any values written to this port should also be stored at $5B5C if any OS routines are in use.

Bit Effect
6-7 Undocumented
5 Lock memory paging (setting to 1 locks pages and cannot be unlocked until next reset)
4 ROM select (low bit of ROM select on +2/+3)
3 Shadow Screen toggle
0-2 Bank number for slot 4 ($C000)