Specifications

Step Event Process BSY DRQ INTRQ

Transfer

first

block

— BSY=0 DRQ=1 Assert

5 Read status BSY=0 DRQ=1 Negate

6 Transfer data BSY=0 DRQ=1 —

7 —

BSY=1

— —

If Error Status is presented, the drive is prepared to transfer data, and it

is at the host’s discretion that the data is transferred. The following

example shows a PIO read command with an error indicated on the first

block. In this example, although DRQ=1 at step 5, there is no valid data

to transfer. Because of the error status, the command is aborted after

step 5.

Step Process BSY DRQ INTRQ

1 Setup BSY=0 — —

Issue command — — —

3 — BSY=1 — —

4 — BSY=0 DRQ=1 Assert

5 Read status BSY=0 DRQ=0 Negate

5.2.2 PIO write commands

PIO write commands include the Format Track, Write Buffer, Write Long,

Write Multiple, Write Same, Write Sectors and Write Verify commands.

The Format Track, Write Buffer and Write Same commands transfer a

single block of 512 bytes. The Write Long command transfers a single

block of 512 bytes plus 4 or more ECC bytes. The Write Multiple

command transfers one or more blocks of data where the size of each

block is a multiple of 512 bytes. The Write Sectors and Write Verify

commands transfer one or more blocks of 512 bytes each.

During a PIO write command, the host and drive follow these steps:

1. The host writes any required parameters to the Features, Sector

Count, Sector Number, Cylinder and Drive/Head registers.

2. The host writes the command code to the Command register.

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28 ATA Interface Reference Manual, Rev. C