IFB Usage Considerations

The drive’s multi word DMA mode capability and current configuration are specified in the IDENTIFY_DRIVE buffer, Words 63 and 65 Software must first check to see that the Words 64-70 are valid before determining the drive’s multi word DMA drive capability.

The drive’s single word DMA mode capability and current configuration are specified in the IDENTIFY_DRIVE buffer, Word 62.

Table 10-3. Identify Device Information Used for Determining Multi/Single Word DMA Drive Capabilities

Capability

Word Offset

Bits

 

Field

 

 

 

 

 

 

 

 

PIO, DMA

53

1

Field Validity

 

 

 

 

 

0: the fields reported in words 64-70 are not valid

 

 

 

1: the fields reported in word 64-70 are valid

 

 

 

 

 

 

DMA

62

10:8

Single Word DMA Modes Active

 

 

 

 

 

bit 10: 1: Single Word DMA Mode

2 is active

 

 

 

 

0: Single Word DMA Mode

2 is not active

 

 

 

bit

9: 1: Single Word DMA Mode

1 is active

 

 

 

 

0: Single Word DMA Mode

1 is not active

 

 

 

bit

8: 1: Single Word DMA Mode

0 is active

 

 

 

 

0: Single Word DMA Mode

0 is not active

 

 

 

 

DMA

62

2:0

Single Word DMA Modes Supported

 

 

 

bit 2: 1: Single Word DMA Mode

2 is supported

 

 

 

 

0: Single Word DMA Mode

2 is not supported

 

 

 

bit 1: 1: Single Word DMA Mode

1 is supported

 

 

 

 

0: Single Word DMA Mode

1 is not supported

 

 

 

bit 0: 1: Single Word DMA Mode

0 is supported

 

 

 

 

0: Single Word DMA Mode

0 is not supported

 

 

 

 

 

 

DMA

63

10:8

Multi Word DMA Modes Active

 

 

 

 

 

bit 10: 1: Multi Word DMA Mode

2 is active

 

 

 

 

0: Multi Word DMA Mode

2 is not active

 

 

 

bit

9: 1: Multi Word DMA Mode

1 is active

 

 

 

 

0: Multi Word DMA Mode

1 is not active

 

 

 

bit

8: 1: Multi Word DMA Mode

0 is active

 

 

 

 

0: Multi Word DMA Mode

0 is not active

 

 

 

 

DMA

63

2:0

Multi Word DMA Modes Supported

 

 

 

bit 2: 1: Multi Word DMA Mode

2 is supported

 

 

 

 

0: Multi Word DMA Mode

2 is not supported

 

 

 

bit 1: 1: Multi Word DMA Mode

1 is supported

 

 

 

 

0: Multi Word DMA Mode

1 is not supported

 

 

 

bit 0: 1: Multi Word DMA Mode

0 is supported

 

 

 

 

0: Multi Word DMA Mode

0 is not supported

 

 

 

 

DMA

65

15:0

Minimum Multi Word DMA Transfer Cycle Time per

 

 

 

Word

 

 

 

 

 

 

 

 

 

To determine the drive’s best DMA capability ensure that the drive reports the capability and is able to transfer at the target cycle time, as shown in Table 10-4.

10-6

Intel® 460GX Chipset Software Developer’s Manual