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IFB Usage Considerations
10-6 Intel® 460GX Chipset Software Developer’s Manual
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.
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.
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