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PhysicalScreen à 2006-05-25 22:25:54.
Physical Screen
On Atari 16/32 bits computers, the
PhysicalScreen is a memory area in RAM where the video system reads the data that is to be rendered on the video monitor. The
LogicalScreen is the memory area where the
VDI draws.
PhysicalScreen and
LogicalScreen are normally the same but they are addressed individually to enable screen flipping.
The address of this buffer can be obtained with a call to the
XBIOS function
Physbase(). When the
_VDO cookie has a value from
0x00000000 to
0x00020000, the size of this buffer has to be guessed with a call to
Getrez() as detailed below:
| Getres()? returns |
screen buffer size |
| 0 |
32000 bytes |
| 1 |
32000 bytes |
| 2 |
32000 bytes |
| 4 |
153600 bytes |
| 6 |
153600 bytes |
| 7 |
153600 bytes |
When the
_VDO cookie has a value of
0x00030000 or greater, the
XBIOS function
Vgetsize() returns the size of the
PhysicalScreen buffer.
See Also