Ide Mode/Drive Feature Settings For Optimal Dma/Pio Operation - Intel 460GX Software Developer’s Manual

IFB Usage Considerations
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.
Table 10-8. IDE Mode/Drive Feature Settings for Optimal DMA/PIO Operation
DMA
IFB IDE IFB IDE
Timing
Drive 0 Drive 1
Enable
Mode Mode
Only
Settings Settings
a
Select 0
Mode 4 Mode 0 Depends
on Drive
Mode 4 Not Depends
Present on Drive
Mode 4 Mode 2 Depends
on Drive
Mode 4 Mode 3 Depends
on Drive
Mode 4 Mode 4 Depends
on Drive
Mode 3 Mode 0 Depends
on Drive
Mode 3 Not Depends
Present on Drive
Mode 3 Mode 2 Depends
on Drive
Mode 3 Mode 3 Depends
on Drive
Mode 3 Mode 4 Depends
on Drive
Mode 2 Mode 0 Depends
on Drive
Mode 2 Not Depends
Present on Drive
Mode 2 Mode 2 Depends
on Drive
Mode 2 Mode 3 Depends
on Drive
Mode 2 Mode 4 Depends
on Drive
Mode 0 Mode 0 Disabled
Mode 0 Not Disabled
Present
Mode 0 Mode 2 Disabled
Mode 0 Mode 3 Disabled
Mode 0 Mode 4 Disabled
a. b. c.
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'.
10-10
IORDY Fast
Pre-Fetch
Sample Timing
and Posting
Point Bank
Enable
Enable Drive
Select 0
b
Select 0 Select 0
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Enabled Enabled
(if fixed disk)
Enabled Depends Enabled
(if fixed disk) on Drive
Enabled Depends Enabled
(if fixed disk) on Drive
Enabled Depends Enabled
(if fixed disk) on Drive
Enabled Depends Enabled
(if fixed disk) on Drive
Enabled Depends Enabled
(if fixed disk) on Drive
Enabled Disabled Disabled
(if fixed disk)
Enabled Disabled Disabled
(if fixed disk)
Enabled Disabled Disabled
(if fixed disk)
Enabled Disabled Disabled
(if fixed disk)
Enabled Disabled Disabled
(if ifxed disk)
DMA IORDY
Pre-Fetch
Timing Sample
and Posting
Enable Point
Enable
Only Enable
Select 1
Select 1 Select 1
Disabled Enabled Disabled
(if fixed disk)
Disabled Disabled Disabled
Depends Enabled Depends
on Drive (if fixed disk) on Drive
Depends Enabled Enabled
on Drive (if fixed disk)
Depends Enabled Enabled
on Drive (if fixed disk)
Disabled Enabled Disabled
(if fixed disk)
Disabled Disabled Disabled
Depends Enabled Depends
on Drive (if fixed disk) on Drive
Depends Enabled Enabled
on Drive (if fixed disk)
Depends Enabled Enabled
on Drive (if fixed disk)
Disabled Enabled Disabled
(if fixed disk)
Disabled Disabled Disabled
Depends Enabled Depends
on Drive (if fixed disk) on Drive
Depends Enabled Enabled
on Drive (if fixed disk)
Depends Enabled Enabled
on Drive (if fixed disk)
Disabled Enabled Disabled
(if fixed disk)
Disabled Disabled Disabled
Depends Enabled Depends
on Drive (if fixed disk) on Drive
Depends Enabled Enabled
on Drive (if fixed disk)
Depends Enabled Enabled
on Drive (if fixed disk)
Intel® 460GX Chipset Software Developer's Manual
Slave IDE
Timing
Register
IDE
Fast Value
Timing
Timing (hex)
Register
Bank bits 3:0
Value
Drive (Primary)
bits 15:8
Select 1 OR
c
(hex)
bits 7:4
(Second-
ary)
All All
speeds speeds
Disabled A3 0
Disabled A3 0
Enabled E3 4
Enabled E3 9
Enabled E3 B
Disabled A1 0
Disabled A1 0
Enabled E1 4
Enabled E1 9
Enabled E1 B
Disabled 90 0
Disabled 90 0
Enabled D0 4
Enabled D0 9
Enabled D0 B
Disabled 80 0
Disabled 80 0
Enabled C0 4
Enabled C0 9
Enabled C0 B
IDE
Timing
Register
Value
bits 7:0
(binary)
0x00xx11
0000xx11
xxx1xx11
xx11xx11
xx11xx11
0x00xx11
0000xx11
xxx1xx11
xx11xx11
xx11xx11
0x00xxx1
0000xxx1
xxx1xxx1
xx11xxx1
xx11xxx1
0000000
0
0000000
0
xxx10000
xx110000
xx110000