Product specifications

VT8601A Apollo PLE133
Revision 1.82 October 22, 2001 -73- VGA Extended Registers
Technologies, Inc.
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VGA Extended Registers
VGA Extended Registers – Non-Indexed I/O Ports
Port 3D8 – Alternate Destination Segment Addr............RW
7 Reserved .........................................always reads 0
6-0 Alternative Destination Segment Address..def = 00
Read / write of this register is enabled by GRF[2].
This register becomes active when GR6[3-2] are not 00.
Port 3D9 – Alternate Source Segment Address...............RW
7 Reserved .........................................always reads 0
6-0 Alternative Source Segment Address .........def = 00
Read / write of this register is enabled by GRF[2].
This register becomes active when GR6[3-2] are not 00.
Port 3xB – Alternate Clock Select....................................RW
3xB notation indicates that this register is accessible at either
3BB or 3DB depending on the setting of the color / mono bit.
7-5 New Mode Control Register Bits 3-1.......... def = 00
These bits have the same function as SRD[3-1]
4-2 Reserved .........................................always reads 0
1-0 Video Clock Select ........................................ def = 00