OSBYTE &70
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 &FA variable.
See also
- OSBYTE &49 - Check for Integra-B shadow memory
- OSBYTE &6C - Select Master/Integra-B shadow memory
- OSBYTE &6F - Select Aries/Watford 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
