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Intel® 460GX Chipset Software Developer’s Manual 10-9
IFB Usage Considerations
10.5.6 IFB Timing Settings
10.5.6.1 DMA/PIO Timing Settings
In Table 10-7, ‘x’=depends on the type of drive installed, ‘1’=enabled, and ‘0’=disabled.
Ultra DMA mode settings are completely independent of the following timings.
Table 10-7. IFB Drive Mode Based on DMA/PIO Capabilities
Drive’s Best
DMA
Capability
Drive’s Best
PIO
Capability
IFB
Timing
Mode
Fast PIO
Supported?
Best PIO
Mode >=
Best DMA
Mode
Non Ultra DMA
Supported?
Best DMA
Mode is {SW2,
MW1, MW2}
DMA
Timing
Enable
Only Select
a
a. Configurations where a drive reports a PIO speed much slower than its reported DMA speed require the DMA Timing Enable Only Select bit to be
Enabled.
Prefetch and
Posting
Enable Select
IORDY
Sample
Point Enable
Select
Fast Timing
Bank Drive
Select
N/A
(DMA not
supported)
PIO0/1/
Compatible
Mode 0 No No Disabled Enabled
(if fixed disk)
Disabled Disabled
N/A
(DMA not
supported)
PIO2 Mode 2 Yes No Disabled Enabled
(if fixed disk)
Depends on
Drive
Enabled
N/A
(DMA not
supported)
PIO3
(w/IORDY)
Mode 3 Yes No Disabled Enabled
(if fixed disk)
Enabled Enabled
N/A
(DMA not
supported)
PIO4
(w/IORDY)
Mode 4 Yes No Disabled Enabled
(if fixed disk)
Enabled Enabled
Single Word
DMA Mode 2
PIO0/1/
Compatible
Mode 2 No (special
config.
needed)
Yes Enabled Enabled
(if fixed disk)
Depends on
Drive
Enabled
Single Word
DMA Mode 2
PIO2 Mode 2 Yes No Disabled Enabled
(if fixed disk)
Depends on
Drive
Enabled
Single Word
DMA Mode 2
PIO3
(w/IORDY)
Mode 2 Yes No Disabled Enabled
(if fixed disk)
Depends on
Drive
Enabled
Single Word
DMA Mode 2
PIO4
(w/IORDY)
Mode 2 Yes No Disabled Enabled
(if fixed disk)
Depends on
Drive
Enabled
Multi Word
DMA Mode 1
PIO0/1/
Compatible/
PIO2
Mode 3 No (special
config.
needed)
Yes Enabled Enabled
(if fixed disk)
Enabled Enabled
Multi Word
DMA Mode 1
PIO3
(w/IORDY)/
PIO4
(w/IORDY)
Mode 3 Yes No Disabled Enabled
(if fixed disk)
Enabled Enabled
Multi Word
DMA Mode 2
PIO0/1/
Compatible/
PIO2
Mode 4 No (special
config.
needed)
Yes Enabled Enabled
(if fixed disk)
Enabled Enabled
Multi Word
DMA Mode 2
PIO3
(w/IORDY)
Mode 3 Yes No Disabled Enabled
(if fixed disk)
Enabled Enabled
Multi Word
DMA Mode 2
PIO4
(w/IORDY)
Mode 4 Yes No Disabled Enabled
(if fixed disk)
Enabled Enabled