VT8601 Via, VT8601 Datasheet - Page 79

• Manufacturer Part Number: VT8601
• Description: Slot-1 / Socket-370 PCI North Bridge
• Manufacturer: Via

VGA CRT Controller Registers (CR)
CRTC registers are accessible at either 3B4 / 3B5 or 3D4 /
3D5 (shorthand notation 3x4 / 3x5) depending on the setting
of Miscellaneous Output Register 3C2 bit-0
Port 3x4 – VGA CRT Controller Index .......................... RW
Port 3x5 Index 0 – VGA CRTC – H Total ...................... RW
Port 3x5 Index 1 – VGA CRTC – H Display Ena End ... RW
Port 3x5 Index 2 – VGA CRTC – H Blank Start ............ RW
Port 3x5 Index 3 – VGA CRTC – H Blank End ............. RW
Port 3x5 Index 4 – VGA CRTC – H Retrace Start......... RW
Port 3x5 Index 5 – VGA CRTC – H Retrace End .......... RW
Port 3x5 Index 6 – VGA CRTC – V Total ....................... RW
Port 3x5 Index 7 – VGA CRTC – Overflow.................... RW
Port 3x5 Index 8 – VGA CRTC – Preset Row Scan ....... RW
Port 3x5 Index 9 – VGA CRTC – Max Scan Line .......... RW
Revision 1.3 September 8, 1999
7-0
7-0
7-0
7-0
6-5
4-0
7-0
6-5
4-0
7-0
6-5
4-0
4-0
7
7
7
6
5
4
3
2
1
0
7
7
6
5
7HFKQRORJLHV ,QF
CRT Controller Index
Only the lower 5 bits are implemented in a standard
VGA to allow access to CRTC registers 0-18h.
However, all 8 bits are implemented here to allow for
extended registers up to index FF.
Horizontal Total....................................... default = 0
Horizontal Display Enable End .............. default = 0
Horizontal Blanking Start ....................... default = 0
Reserved
Display Enable Skew................................ default = 0
Horizontal Blanking End......................... default = 0
Horizontal Retrace Pulse Start ......... default = 0FFh
Horizontal Blanking End......................... default = 0
Horizontal Retrace Delay ........................ default = 0
Horizontal Retrace Pulse End................. default = 0
Vertical Total ........................................... default = 0
Vertical Retrace Start Bit-9 .................... default = 0
Vertical Display Enable End Bit-9.......... default = 0
Vertical Total Bit-9 .................................. default = 0
Line Compare Bit-8 ................................. default = 0
Vertical Blank Start Bit-8 ....................... default = 0
Vertical Retrace Start Bit-8 ................... default = 0
Vertical Display Enable End Bit-8.......... default = 0
Vertical Total Bit-8 .................................. default = 0
Reserved
Byte Panning ............................................ default = 0
Preset Row Scan....................................... default = 0
200 to 400 Line Conversion..................... default = 0
Line Compare Bit-9 ................................. default = 0
Vertical Blank Start Bit-9 ....................... default = 0
Maximum Scan Line ................................ default = 0
:H &
:H &R R QQHFW
QQHFW
........................................ always reads 0
........................................ always reads 0
-73
Port 3x5 Index A – VGA CRTC – Cursor Start ............ RW
Port 3x5 Index B – VGA CRTC – Cursor End .............. RW
Port 3x5 Index C / D – VGA CRTC Start Addr Hi/Lo .. RW
Port 3x5 Index E / F – VGA CRTC Cursor Loc Hi/Lo . RW
Port 3x5 Index 10 – VGA CRTC – V Retrace Start ...... RW
Port 3x5 Index 11 – VGA CRTC – V Retrace End ........ RW
Port 3x5 Index 12 – VGA CRTC – V Display Ena End RW
Port 3x5 Index 13 – VGA CRTC – Offset....................... RW
Port 3x5 Index 14 – VGA CRTC – Underline Location RW
Port 3x5 Index 15 – VGA CRTC – V Blank Start ......... RW
Port 3x5 Index 16 – VGA CRTC – V Blank End ........... RW
Port 3x5 Index 17 – VGA CRTC – Mode Control ......... RW
Port 3x5 Index 18 – VGA CRTC – Line Compare ........ RW
7-6
4-0
6-5
4-0
7-0
3-0
7-0
7-0
4-0
7-0
7-0
7-0
5
7
7
6
5
4
7
6
5
7
6
5
4
3
2
1
0
Reserved
Cursor On/Off ..........................................default = 0
Cursor Row Scan Start ............................default = 0
Reserved
Cursor Skew.............................................. default = 0
Cursor Row Scan End..............................default = 0
Vertical Retrace Pulse Start ....................default = 0
CR0-7 Write Protect ................................ default = 0
Reserved
Vertical Interrupt Enable ........................ default = 0
Vertical Interrupt Clear .......................... default = 0
Vertical Retrace Pulse End...................... default = 0
Vertical Display Enable End ...................default = 0
Display Screen Logical Line Width ........ default = 0
Reserved
Double Word Mode..................................default = 0
Count By 4 ............................................. default = 0
Underline Location...................................default = 0
Vertical Blanking Start ............................default = 0
Vertical Blanking End..............................default = 0
Hardware Rese ......................................... default = 0
Word / Byte Mode ....................................default = 0
Address Wrap ........................................... default = 0
VSYNC Update Select (VGA Extended Capability)
Count By 2 .............................................. default = 0
Horizzontal Retrace Select ...................... default = 0
Select Row Scan Counter......................... default = 0
Compatibility Mode Support................... default = 0
Line Compare ...........................................default = 0
0
1
Base may only be updated during Vsync ..... def
Base address may be updated during Hsync
........................................always reads 0
........................................always reads 0
.............................................. default = 0
.............................................. default = 0
........................................always reads 0
........................................always reads 0
VT8601 Apollo ProMedia
VGA Registers