Intel 460GX Computer Hardware User Manual


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IFB Usage Considerations
10-10 Intel® 460GX Chipset Software Developer’s Manual
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.
NOTES:
1. DMA Timing Enable Only field is in general Disabled. It is only Enabled in certain cases if the DMA Mode capability of the drive
is much greater than the PIO Mode capability of the drive.
2. The IORDY Sample Point field must be Enabled for PIO Modes 3 and 4. It is Enabled on PIO2 drives if and only if IORDY
capability is supported in the drive.
3. The above recommendations assume that if the attached slave drive is Mode 0 or not present, SITRE bit is ’0’.
Table 10-8. IDE Mode/Drive Feature Settings for Optimal DMA/PIO Operation
IFB IDE
Drive 0
Mode
Settings
IFB IDE
Drive 1
Mode
Settings
DMA
Timing
Enable
Only
Select 0
a
a.
Pre-Fetch
and Posting
Enable
Select 0
IORDY
Sample
Point
Enable
Select 0
b
b.
Fast
Timing
Bank
Drive
Select 0
DMA
Timing
Enable
Only
Select 1
Pre-Fetch
and Posting
Enable
Select 1
IORDY
Sample
Point
Enable
Select 1
Fast
Timing
Bank
Drive
Select 1
IDE
Timing
Register
Value
bits 15:8
(hex)
c
c.
Slave IDE
Timing
Register
Value
(hex)
bits 3:0
(Primary)
OR
bits 7:4
(Second-
ary)
IDE
Timing
Register
Value
bits 7:0
(binary)
All
speeds
All
speeds
Mode 4 Mode 0 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Disabled Enabled
(if fixed disk)
Disabled Disabled A3 0 0x00xx11
Mode 4 Not
Present
Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Disabled Disabled Disabled Disabled A3 0 0000xx11
Mode 4 Mode 2 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled E3 4 xxx1xx11
Mode 4 Mode 3 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled E3 9 xx11xx11
Mode 4 Mode 4 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled E3 B xx11xx11
Mode 3 Mode 0 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Disabled Enabled
(if fixed disk)
Disabled Disabled A1 0 0x00xx11
Mode 3 Not
Present
Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Disabled Disabled Disabled Disabled A1 0 0000xx11
Mode 3 Mode 2 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled E1 4 xxx1xx11
Mode 3 Mode 3 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled E1 9 xx11xx11
Mode 3 Mode 4 Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled E1 B xx11xx11
Mode 2 Mode 0 Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled Disabled Enabled
(if fixed disk)
Disabled Disabled 90 0 0x00xxx1
Mode 2 Not
Present
Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled Disabled Disabled Disabled Disabled 90 0 0000xxx1
Mode 2 Mode 2 Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled D0 4 xxx1xxx1
Mode 2 Mode 3 Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled D0 9 xx11xxx1
Mode 2 Mode 4 Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled D0 B xx11xxx1
Mode 0 Mode 0 Disabled Enabled
(if fixed disk)
Disabled Disabled Disabled Enabled
(if fixed disk)
Disabled Disabled 80 0 0000000
0
Mode 0 Not
Present
Disabled Enabled
(if fixed disk)
Disabled Disabled Disabled Disabled Disabled Disabled 80 0 0000000
0
Mode 0 Mode 2 Disabled Enabled
(if fixed disk)
Disabled Disabled Depends
on Drive
Enabled
(if fixed disk)
Depends
on Drive
Enabled C0 4 xxx10000
Mode 0 Mode 3 Disabled Enabled
(if fixed disk)
Disabled Disabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled C0 9 xx110000
Mode 0 Mode 4 Disabled Enabled
(if ifxed disk)
Disabled Disabled Depends
on Drive
Enabled
(if fixed disk)
Enabled Enabled C0 B xx110000
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