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3.2.2.1 PIO and DMA Data-Transfer Modes
You can set the multiword DMA mode and identify the PIO data-transfer
mechanism and transfer mode with the Set Features command. To set
the multiword DMA mode:
1.1.
Write Set Features command value 03
H
(Set Data Transfer mode) to
the Features register.
2.
Write a transfer types value to the Sector Count register. The upper 5
bits of this value define the type of data transfer, and the lower 3 bits
encode the mode value. This changes word 63 of the Identify Drive
command to the value you enter in the Sector Count register.
The following table identifies allowable transfer types values:
Data-Transfer Mechanism Transfer Types value
Mechanism name
Mode
value
Data
Upper 5 bits
Lower 3 bits
PIO Transfer Mode (default) 2 00000 000
PIO Transfer Mode: Disable
IORDY Set PIO Mode = 2
2 00000 001
PIO Flow Control Transfer
Mode: Set PIO Mode = 0
0 00001 000
PIO Flow Control Transfer
Mode: Set PIO Mode = 1
1 00001 001
PIO Flow Control Transfer
Mode: Set PIO Mode = 2
2 00001 010
PIO Flow Control Transfer
Mode: Set PIO Mode = 3
3 00001 011
PIO Flow Control Transfer
Mode: Set PIO Mode = 4)
4 00001 100
Obsolete 00010
nnn
Multiword DMA Mode 0 00100 000
Multiword DMA Mode 1 00100 001
Multiword DMA Mode 2 00100 010
Synchronous DMA Mode 01000
nnn
Reserved — 10000
nnn
Note.
If the drive does not support a commanded mode, it returns a 04
aborted command error.
Medalist Pro 6450/6451 Product Manual, Rev. B 33