VT8601 Via, VT8601 Datasheet - Page 81

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

VGA Extended Registers – Sequencer Indexed
SR8 – Old / New Status ...................................................... RO
SR9 – Graphics Controller Version .................................. RO
SRB – Version / Old-New Mode Control ........................ RW
A write to this register will change the Old / New Mode
Control registers (SRD, SRE, and GRE) to the “old”
definition. A read from this register will change the Old / New
Mode Control registers to the “new” definition.
SRC – Configuration Port 1 ............................................. RW
Access to this register is enabled by SRE_Old[5] = 1 (“Select
Configuration Port 1”) and writes are enabled by SRE_New[7]
= 1 (“Configuration Port Write Enable”).
SRC – Configuration Port 2 ............................................. RW
Access to this register is enabled by SRE_Old[5] = 0 (“Select
Configuration Port 2”) and writes are enabled by SRE_New[7]
= 1 (“Configuration Port Write Enable”).
Revision 1.3 September 8, 1999
3-0
7-0
7-0
2-0
7-0
7
6
5
4
7
6
5
4
3
7HFKQRORJLHV ,QF
Old / New Status (see SRB, SRC, SRD, SRE, GRE)
Interlace Scan Field
Reserved
Command FIFO Empty
Reserved
Version Number ............................. always reads 58h
Graphics Controller Version #...... always reads F3h
Reserved
Memory Bus Width
Note: Although the ProMedia integrated graphics
controller does not control memory directly (the
system memory controller is used to access graphics
memory as a portion of system memory), some
functional blocks in the graphics controller (such as
video) use this bit to manage their data bus widths.
Reserved
Video Subsystem Enable
Video BIOS Size
Reserved
Reserved for BIOS
:H &
:H &R R QQHFW
0
1
0
1
0
1
0
1
0
1
0
1
QQHFW
Old
New
Odd
Even
Empty .....................................................default
Not Empty
32-bit Memory Bus ................................default
64-bit Memory Bus
46E8
3C3
64K .....................................................default
32K
.....................................................default
.....................................................default
........................................ always reads 0
........................................ always reads 0
....................................... always reads 1
....................................... always reads 1
.....................................................default
.................................always reads 111b
-75
SRD – Mode Control 2 (Old) ........................................... RW
SRD – Mode Control 2 (New) .......................................... RW
7-6
2-0
7-4
2-1
5
4
3
3
0
Reserved
Reserved
Reserved
CPU Bandwidth Select
Reserved
Display FIFO Memory Request Threshold Ctrl
Reserved
Video Clock Divide
Reserved
0000 Empty 0 level
0001 Empty 4 level......................................... default
0010 Empty 8 lrevel
0011 Empty 12 level
0100 Empty 16 level
0101 Empty 20 level
0110 Empty 24 level
0111 Empty 28 level
1000 Empty 32 level
1001 Empty 36 level
1010 Empty 40 level
1011 Empty 44 level
1100 Empty 48 level
1101 Empty 52 level
1110 Empty 56 level
1111 Empty 60 level
00 Divide by 1 ............................................ default
01 Divide by 2
10 Divide by 4
11 Divide by 1.5
0
1
Normal................................................... default
Non-interrupted CPU access during VBLANK
........................................always reads 0
...................................... always reads 1
........................................always reads 0
........................................always reads 0
........................................always reads 0
........................................always reads 0
VT8601 Apollo ProMedia
VGA Extended Registers