Difference between revisions of "OSBYTE &70"

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m (Added Integra-B info.)
m (Added return value and variable location.)
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     On entry:
 
     On entry:
         X=0 Use whatever the default for the current mode is
+
         X=0 Use whatever memory the current screen MODE uses
 
         X=1 Use main memory
 
         X=1 Use main memory
 
         X=2 Use shadow memory
 
         X=2 Use shadow memory
 +
    On exit:
 +
        X=preserved
 
     RISC OS:
 
     RISC OS:
 
     The value of X can be greater than 2 as well, and instructs the VDU
 
     The value of X can be greater than 2 as well, and instructs the VDU
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of memory while the other is being displayed.
 
of memory while the other is being displayed.
  
==See Also==
+
The setting is stored in the [[OSBYTE &F0]] variable.
 +
 
 +
==See also==
 
* [[OSBYTE &49]] - Check for Integra-B shadow memory
 
* [[OSBYTE &49]] - Check for Integra-B shadow memory
 
* [[OSBYTE &6C]] - Select Master/Integra-B shadow memory
 
* [[OSBYTE &6C]] - Select Master/Integra-B shadow memory
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* http://mdfs.net/Docs/Comp/BBC/Osbyte00
 
* http://mdfs.net/Docs/Comp/BBC/Osbyte00
  
[[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 20:30, 3 April 2015 (UTC)
+
[[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 01:11, 4 April 2015 (UTC)

Revision as of 02:11, 4 April 2015

OSBYTE &70 (112) - Select Main/Shadow for VDU access

   On entry:
       X=0 Use whatever memory the current screen MODE uses
       X=1 Use main memory
       X=2 Use shadow memory
   On exit:
       X=preserved
   RISC OS:
   The value of X can be greater than 2 as well, and instructs the VDU
   drivers to use the bank at screenbase+(X*modesize)

This call specifies which bank of memory the Master VDU drivers access. Using this and OSBYTE &71 a program can use the VDU to write to one bank of memory while the other is being displayed.

The setting is stored in the OSBYTE &F0 variable.

See also

Jgharston (talk) 01:11, 4 April 2015 (UTC)