User Manual

ATA Command Description

5-10 CompactFlash

5.1.8. Initialize Drive Parameters—91H

Table 5-11. Initialize Drive Parameters

Bit -> 7 6 5 4 3 2 1 0

Command (7) 91H

C/D/H (6) X 0 X Drive Max Head (no. of heads-1)

Cyl High (5) X

Cyl Low (4) X

Sec Num (3) X

Sec Cnt (2) Number of Sectors

Feature (1) X

This command enables the host to set the number of sectors per track and the number of heads per cylinder. Only the

Sector Count and the Card/Drive/Head registers are used by this command.

NOTE: SanDisk recommends NOT using this command in any system because DOS determines the offset to the

Boot Record based on the number of heads and sectors per track. If a CompactFlash Memory Card is

“Formatted” with one head and sector per track value, the same CompactFlash Card will not operate

correctly with DOS configured with another heads and sectors per track value.

5.1.9. Read Buffer—E4H

Table 5-12. Read Buffer

Bit -> 7 6 5 4 3 2 1 0

Command (7) E4H

C/D/H (6) X Drive X

Cyl High (5) X

Cyl Low (4) X

Sec Num (3) X

Sec Cnt (2) X

Feature (1) X

The Read Buffer command enables the host to read the current contents of the CompactFlash Memory Card’s sector

buffer. This command has the same protocol as the Read Sector(s) command.