IFB Usage Considerations

Table 10-11. Ultra DMA/Multi Word DMA/Single Word Transfer/Mode Values

 

 

 

ATA SET_FEATURES -

Drive’s Selected Ultra

Drive’s Selected Non-

Selected Speed

Command Set Transfer

Mode Sub Command

DMA Capability

ultra DMA Capability

 

Parameter for Selected

 

 

 

 

 

 

Speed

 

 

 

 

Ultra DMA Mode 2

any

Ultra DMA Mode 2

42h

 

 

 

 

Ultra DMA Mode 1

any

Ultra DMA Mode 1

41h

 

 

 

 

Ultra DMA Mode 0

any

Ultra DMA Mode 0

40h

 

 

 

 

N/A

Multi Word DMA Mode 2

Multi Word DMA Mode 2

22h

 

 

 

 

N/A

Multi Word DMA Mode 1

Multi Word DMA Mode 1

21h

 

 

 

 

N/A

Single Word DMA Mode

Single Word DMA Mode

12h

 

2

2

 

 

 

 

 

N/A

N/A

Disabled

N/A

 

 

 

 

Refer to the Set Features Command description in the ATA Specification for more information.

Table 10-12. PIO Transfer/Mode Values

Drive’s Selected PIO Speed Capability

ATA SET_FEATURES -Command Set Transfer Mode

Sub Command Parameter for Selected Speed

 

 

 

PIO0/PIO1/PIO2/Compatible

N/A

 

 

PIO3 w/IORDY Flow Control

C3

 

 

PIO4 w/IORDY Flow Control

C4

 

 

A drive may only be enabled for a Single DMA capability. In general, if a drive supports a supported Ultra DMA speed, then Ultra DMA is configured for the drive. If a drive does not support Ultra DMA, then it should be configured with it’s selected DMA speed, if it exists. If a drive supports only PIO (does not have support for either Ultra DMA or DMA speeds), then the drive shall only be accessed in a PIO mode only.

If a drive is configured for an Ultra DMA speed or a DMA speed, its corresponding DMA-capable bit in the PCI Bus Master I/O Status Register (Primary: PCI Bus Master IDE I/O Offset + 02h; Secondary - PCI Bus Master I/O Offset + 0Ah) MUST be set. This will allow PCI Bus Master IDE capable device drivers to recognize the fact that this drive has been identified and configured by the firmware for PCI Bus Master IDE operation.

10-12

Intel® 460GX Chipset Software Developer’s Manual