OSBYTE &71

From BeebWiki
Revision as of 19:28, 22 January 2021 by Jgharston (talk | contribs) (See Also)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search
OSBYTE &71 (113) - Select Main/Shadow for Display
   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 video
   hardware to use the bank at screenbase+(X*modesize)

This call specifies which bank of memory the Master video display hardware accesses. Using this and OSBYTE &70 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 &FB variable.

See also


Jgharston (talk) 01:12, 4 April 2015 (UTC)