Memory Paging Control

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Revision as of 15:21, 28 August 2017 by wiki>Hyphz
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Number $7FFD
Short desc. Selects active RAM, ROM, and displayed screen.
Bit Mask %01------------0c
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)