READ ID
DATA BUS
PHASE
R/W D7
D6
MFM
0
D5 D4 D3
D2
D1
D0
REMARKS
Commands
Command
W
W
0
0
0
0
0
0
1
0
0
1
0
HDS DS1 DS0
Execution
The first correct ID
information on the
Cylinder is stored in
Data Register
Result
R
──────── ST0 ────────
Status information after
Command execution.
R
R
R
R
R
R
──────── ST1 ────────
──────── ST2 ────────
──────── C ────────
──────── H ────────
──────── R ────────
──────── N ────────
PERPENDICULAR MODE
DATA BUS
PHASE
R/W
D7
0
D6 D5 D4 D3 D2
D1
D0
REMARKS
Command
W
0
0
0
1
0
0
1
0
Command Codes
OW
D3 D2 D1 D0
GAP
WGATE
INVALID CODES
DATA BUS
PHASE
R/W D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
Command
W
───── Invalid Codes ─────
Invalid Command Codes
(NoOp - FDC goes into Stand-
by State)
Result
R
─────── ST0 ───────
ST0 = 80H
LOCK
DATA BUS
PHASE
Command
Result
R/W
W
D7
LOCK
0
D6 D5
D4
1
D3 D2 D1 D0
REMARKS
0
0
0
0
0
0
1
0
0
0
0
0
Command Codes
R
LOCK
SC is returned if the last command that was issued was the Format command. EOT is returned if the last command was
a Read or Write.
Note: These bits are used internally only. They are not reflected in the Drive Select pins. It is the user's responsibility to
maintain correspondence between these bits and the Drive Select pins (DOR).
DATA TRANSFER COMMANDS
All of the Read Data, Write Data and Verify type commands use the same parameter bytes and return the same results
information, the only difference being the coding of bits 0-4 in the first byte.
An implied seek will be executed if the feature was enabled by the Configure command. This seek is completely
transparent to the user. The Drive Busy bit for the drive will go active in the Main Status Register during the seek portion
of the command. If the seek portion fails, it is reflected in the results status normally returned for a Read/Write Data
command. Status Register 0 (ST0) would contain the error code and C would contain the cylinder on which the seek
failed.
Read Data
A set of nine (9) bytes is required to place the FDC in the Read Data Mode. After the Read Data command has been
issued, the FDC loads the head (if it is in the unloaded state), waits the specified head settling time (defined in the
Specify command), and begins reading ID Address Marks and ID fields. When the sector address read off the diskette
SMSC LPC47B27x
- 44 -
Rev. 08-10-04
DATASHEET
SMSC [ SMSC CORPORATION ]
