Difference between revisions of "OSBYTE &70"
m (Added Integra-B info.) |
m (Added return value and variable location.) |
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| Line 3: | Line 3: | ||
On entry: | On entry: | ||
| − | X=0 Use whatever | + | 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 | ||
| Line 14: | Line 16: | ||
of memory while the other is being displayed. | of memory while the other is being displayed. | ||
| − | ==See | + | 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 | ||
| Line 26: | Line 30: | ||
* http://mdfs.net/Docs/Comp/BBC/Osbyte00 | * http://mdfs.net/Docs/Comp/BBC/Osbyte00 | ||
| − | [[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) | + | [[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
- OSBYTE &49 - Check for Integra-B shadow memory
- OSBYTE &6C - Select Master/Integra-B shadow memory
- OSBYTE &6F - Select BBC B shadow memory
- OSBYTE &70 - Select memory for Master VDU access
- OSBYTE &71 - Select memory for Master video display
- OSBYTE &72 - Select future use of shadow memory
- OSBYTE &73 - Select shadow bank
- OSBYTE &74 - Check for Solidisk shadow memory
- Paging in video memory
- http://mdfs.net/Docs/Comp/BBC/Osbyte00
