Product specifications

VT8601A Apollo PLE133
Revision 1.82 October 22, 2001 -71- VGA Registers
Technologies, Inc.
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VGA Graphics Controller Registers (GR)
Port 3CE – VGA Graphics Controller Index..................RW
7 Reserved .........................................always reads 0
6-0 Graphics Controller Index
Only the lower 4 bits are implemented in a standard
VGA to allow access to Graphics Controller registers
0-8. However, 7 bits are implemented here to allow
for extended registers up to index 7F.
Port 3CF Index 0 – Graphics Controller Set / Reset ......RW
7-4 Reserved .........................................always reads 0
3-0 Set / Reset Planes 3-0
Port 3CF Index 1 – Graphics Controller Set / Reset EnaRW
7-4 Reserved .........................................always reads 0
3-0 Enable Set / Reset Planes 3-0
Port 3CF Index 2 – Graphics Controller Color CompareRW
7-4 Reserved .........................................always reads 0
3-0 Color Compare Planes 3-0
Port 3CF Index 3 – Graphics Controller Data Rotate....RW
7-4 Reserved .........................................always reads 0
3 Function Select
2-0 Rotate Count
Port 3CF Index 4 – Graphics Ctrlr Read Map Select ....RW
7-2 Reserved .........................................always reads 0
1-0 Map Select
Port 3CF Index 5 – Graphics Controller Mode..............RW
7 Reserved .........................................always reads 0
6 256 Color Mode......................................... default = 0
5 Shift Register............................................. default = 0
4 Odd / Even ............................................... default = 0
3 Read Mode ............................................... default = 0
2 Reserved .........................................always reads 0
1-0 Write Mode ............................................... default = 0
Port 3CF Index 6 – Graphics Controller MiscellaneousRW
7-4 Reserved .........................................always reads 0
3-2 Memory Map
1 Chain Odd Maps to Even
0 Graphics Mode
Port 3CF Index 7 – Graphics Ctrlr Color Don’t Care...RW
7-4 Reserved .........................................always reads 0
3-0 Color Don’t Care Planes 3-0
Port 3CF Index 8 – Graphics Controller Bit Mask ........RW
7-0 Bit Mask