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.
- 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