Product manual

Preliminary CompactFlash Memory Card Product Manual

6.0 ATA Command Description

This section defines the software requirements and

the format of the commands the host sends to the

CompactFlash Memory Cards. Commands are

issued to the CompactFlash Card by loading the

required registers in the command block with the

supplied parameters, and then writing the

command code to the Command Register. The

manner in which a command is accepted varies.

There are three classes (see Table 6-1) of command

acceptance, all dependent on the host not issuing

commands unless the CompactFlash Card is not

busy. (The BUSY bit in the status and alternate

status registers is 0.)

• Upon receipt of a Class 1 command, the

CompactFlash Card sets the BUSY bit within

400 nsec.

• Upon receipt of a Class 2 command, the

CompactFlash Memory Card sets the BUSY bit

within 400 nsec, sets up the sector buffer for a

write operation, sets DRQ within 700 µsec, and

clears the BUSY bit within 400 nsec of setting

DRQ.

• Upon receipt of a Class 3 command, the

CompactFlash Memory Card sets the BUSY bit

within 400 nsec, sets up the sector buffer for a

write operation, sets DRQ within 20 msec

(assuming no re-assignments), and clears the

BUSY bit within 400 nsec of setting DRQ.

6.1 ATA Command Set

Table 6-1 summarizes the ATA command set with

the paragraphs that follow describing the

individual commands and the task file for each.