IFB Usage Considerations

into the system firmware by the vendor. This reporting will make these register locations safe and the OS will not use these locations randomly if a PNP conflicting device is relocatable in those I/O or memory locations. These locations also got to be reported to the OS whenever the OEM sends the systems for their WHQL suite test.

10.5Ultra DMA Configuration

The following registers are programmed in systems that contain devices that implement the Ultra DMA Protocol. These registers allow Ultra DMA to be used when PCI Bus Master IDE operation is initiated by the device driver.

10.5.1UDMAC–Ultra DMA Control Register (IFB Function 1 PCI Configuration Offset 48h)

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

Reserved

 

 

 

Secondary

Secondary

Primary

Primary

 

 

 

 

Drive 1

Drive 0

Drive 1

Drive 0

 

 

 

 

Ultra DMA

Ultra DMA

Ultra DMA

Ultra DMA

 

 

 

 

Mode

Mode

Mode

Mode

 

 

 

 

Enable

Enable

Enable

Enable

 

 

 

 

(SSDE1)

(SSDE0)

(PSDE1)

(PSDE0)

 

 

 

 

 

 

 

 

 

 

 

 

0: Disabled

0: Disabled

0: Disabled

0: Disabled

 

 

 

 

1: Enabled

1: Enabled

1: Enabled

1: Enabled

 

 

 

 

 

 

 

 

10.5.2UDMATIM–Ultra DMA Timing Register (IFB Function 1 PCI Configuration Offsets 4A-4Bh)

15

14

13

 

12

11

10

9

 

8

 

 

 

 

 

 

 

 

Reserved

 

Secondary Drive 1

Reserved

 

Secondary Drive 0

 

 

Ultra DMA Cycle Time

 

 

Ultra DMA Cycle Time

 

 

(SCT1)

 

 

 

(SCT1)

 

 

 

 

 

 

 

 

 

00: CT=4 clks, RP=6 clks

 

 

00: CT=4 clks, RP=6 clks

 

 

01: CT=3 clks, RP=5 clks

 

 

01: CT=3 clks, RP=5 clks

 

 

10: CT=2 clks, RP=4 clks

 

 

10: CT=2 clks, RP=4 clks

 

 

11: Reserved

 

 

 

11: Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

6

5

 

4

3

2

1

 

0

 

 

 

 

 

 

 

 

 

 

Reserved

 

Primary Drive 1

 

Reserved

 

Primary Drive 0

 

 

 

Ultra DMA Cycle Time

 

 

Ultra DMA Cycle Time

 

 

(PCT1)

 

 

 

(PCT1)

 

 

 

 

 

 

 

 

 

00: CT=4 clks, RP=6 clks

 

 

00: CT=4 clks, RP=6 clks

 

 

01: CT=3 clks, RP=5 clks

 

 

01: CT=3 clks, RP=5 clks

 

 

10: CT=2 clks, RP=4 clks

 

 

10: CT=2 clks, RP=4 clks

 

 

11: Reserved

 

 

 

11: Reserved

 

 

 

 

 

 

 

 

 

 

 

10-2

Intel® 460GX Chipset Software Developer’s Manual