Product specifications

VT8235 V-Link South Bridge
Revision 1.22 October 24, 2002 -95- Device 17 Function 1 Enhanced IDE Controller Registers
IDE-Controller-Specific Configuration Registers
Offset 40 - Chip Enable (00h)...........................................RW
7-2 Reserved ........................................ always reads 0
1 Primary Channel
0 Disable .................................................. default
1 Enable
0 Secondary Channel
0 Disable .................................................. default
1 Enable
Offset 41 - IDE Configuration I (00h)..............................RW
7 Primary IDE Read Prefetch Buffer
0 Disable .................................................. default
1 Enable
6 Primary IDE Post Write Buffer
0 Disable .................................................. default
1 Enable
5 Secondary IDE Read Prefetch Buffer
0 Disable .................................................. default
1 Enable
4 Secondary IDE Post Write Buffer
0 Disable .................................................. default
1 Enable
3-0 Reserved ........................................ always reads 0
Offset 42 - IDE Configuration II (00h)............................RW
7 PIO Operating Mode - Primary Channel
Selects the mode used in the primary channel for the
I/O Base Address (not IRQ routing or sharing)
0 Compatibility Mode (fixed addressing). default
1 Native PCI Mode (flexible addressing)
6 PIO Operating Mode - Secondary Channel
Selects the mode used in the secondary channel for
the I/O Base Address (not IRQ routing or sharing)
0 Compatibility Mode (fixed addressing). default
1 Native PCI Mode (flexible addressing)
5-0 Reserved ........................................ always reads 0
Offset 43 - FIFO Configuration (0Ah) ............................ RW
7-4 Reserved ........................................always reads 0
3-2 Primary Channel FIFO Threshold
Determines the threshold required before the primary
channel FIFO is flushed.
00 FIFO flushed when 1/4 full
01 FIFO flushed when 1/2 full
10 FIFO flushed when 3/4 full...................default
11 FIFO flushed when completely full (32 DWs)
1-0 Secondary Channel FIFO Threshold
Determines the threshold required before the
secondary channel FIFO is flushed.
00 FIFO flushed when 1/4 full
01 FIFO flushed when 1/2 full
10 FIFO flushed when 3/4 full...................default
11 FIFO flushed when completely full (32 DWs)