SS.SLGBf Set Status
From NitrOS-9
Selects a graphics buffer.
| Entry Conditions | |
| A | path number |
| B | SS.SLGBf ($81) |
| X | $00 select buffer for use |
| $01-$FF select buffer for use and display | |
| Y | buffer number (0-2) |
| Exit Conditions | |
| X | unchanged from entry |
| Y | unchanged from entry |
| Error Output | |
| CC | carry set on error |
| B | error code |
Additional Information
- Use DISPLAY GRAPHICS to allocate the first graphics buffer. Use SS.AAGBf to allocate the second and third graphics buffers.
- Save each return address when writing directly to a screen. It is not necessary to save return addresses when using operating system graphics commands.
- SS.SLGBf does not update hardware information until the next vertical retrace (60Hz rate). Programs that use SS.AAGBf to change current draw buffers need to wait long enough to ensure that OS-9 has moved the current buffer to the screen.
- The screen shows the buffer only if the buffer is selected as the interactive device. If the device does not possess the keyboard, OS-9 stores the information until the device is selected as the interactive device. When the device is selected as the interactive device, the display shows the selected device's screen.
- The support module for this call is VDGINT.
