HOST SOFTWARE INTERFACE
Command Register
Contains code for the command to be performed. Additional command information should be written to the task file before
the Command register is loaded. When this register is written, the BUSY bit in the Status register sets, and interrupt request to
the host clears; invalid commands abort. (Detailed information on interface commands is given in Section 7.) Hex values for
valid command formats follow:
Read Commands
Read Sector(s)
Read Verify Sector(s)
Read Sector Buffer
Read Multiple
Read DMA
Write Commands
Write Sector(s)
Write Verify Sector(s)
Write Sector Buffer
Write Multiple
Write DMA
Mode Set/Check Commands
Set Features
Set Multiple Mode
Power Mode Commands
Standby Immediate
Idle Immediate
Standby
Idle
Check Power Mode
Set Sleep Mode
Initialization Commands
Identify Drive
Initialize Drive Parameters
Re-calibrate
Seek, Format, and Diagnostic Commands
Seek
Format Track
Execute Drive Diagnostic
S.M.A.R.T. Commands
Execute S.M.A.R.T.
6 – 36
20h
Normal reads; retries enabled
21h
Normal reads; retries disabled
22h
Read Long; retries enabled
23h
Read Long; retries disabled
40h
Retries enabled
41h
Retries disabled
E4h
C4h
C8h
C9h
No retries
30h
Normal writes; retries enabled
31h
Normal writes; retries disabled
32h
Write Long; retries enabled
33h
Write Long; retries disabled
3Ch
E8h
C5h
CAh
CBh
No retries
EFh
C6h
94/E0h
Stops drive spindle; do not change time-out value
95/E1h
Starts spindle; do not change time-out value
96/E2h
Stops spindle; change time-out value
97/E3h
Starts spindle; change time-out value
98/E5h
99/E6h
ECh
91h
1xh
7xh
50h
90h
B0h