Difference between revisions of "Plus 3 Memory Paging Control"

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! Bit !! Effect  
 
! Bit !! Effect  
 
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| 5-7 || Undocumented, may be used for extra bits of slot 4 bank select (see {{PortNo|$7FFD}}
+
| 5-7 || Undocumented, may be used for extra bits of slot 4 bank select (see {{PortNo|$7FFD}})
 
|-
 
|-
 
| 4 || Printer Port Strobe
 
| 4 || Printer Port Strobe

Revision as of 23:49, 18 August 2017

Number $1FFD
Decimal
Short desc. Controls ROM paging and special paging options from the +2a/+3.
Bit Mask
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 Memory Paging Control ($7FFD / 32765))
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.