SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 86

• Manufacturer Part Number: SCH3112I-NE
• Description: LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
• Manufacturer: SMSC [SMSC Corporation]

Rev 0.2 (09-28-04)
5.25” Drives
3.5” Drives
3.5” Drives
GPL1 = suggested GPL values in Read and Write commands to avoid splice point between data field and
field of contiguous sections.
GPL2 = suggested GPL value in Format A Track command.
*PC/AT values (typical)
**PS/2 values (typical). Applies with 1.0 MB and 2.0 MB drives.
Note:
All values except sector size are in hex.
CONTROL COMMANDS
Control commands differ from the other commands in that no data transfer takes place. Three
commands generate an interrupt when complete: Read ID, Re calibrate, and Seek. The other control
commands do not generate an interrupt.
Read ID
The Read ID command is used to find the present position of the recording heads. The FDC stores
the values from the first ID field it is able to read into its registers. If the FDC does not find an ID
address mark on the diskette after the second occurrence of a pulse on the nINDEX pin, it then sets
the IC code in Status Register 0 to “01” (abnormal termination), sets the MA bit in Status Register 1
to “1”, and terminates the command.
The following commands will generate an interrupt upon completion. They do not return any result
bytes. It is highly recommended that control commands be followed by the Sense Interrupt Status
command. Otherwise, valuable interrupt status information will be lost.
Recalibrate
This command causes the read/write head within the FDC to retract to the track 0 position. The FDC
clears the contents of the PCN counter and checks the status of the nTRK0 pin from the FDD. As
long as the nTRK0 pin is low, the DIR pin remains 0 and step pulses are issued. When the nTRK0
pin goes high, the SE bit in Status Register 0 is set to “1” and the command is terminated. If the nTRK0
pin is still low after 79 step pulses have been issued, the FDC sets the SE and the EC bits of Status
Register 0 to “1” and terminates the command. Disks capable of handling more than 80 tracks per side
may require more than one Recalibrate command to return the head back to physical Track 0.
FORMAT
MFM
MFM
FM
FM
Table 7.22 Typical Values for Formatting
SECTOR
512**
SIZE
1024
2048
4096
1024
2048
4096
1024
512*
128
128
512
256
256
128
256
512
256
...
...
DATASHEET
LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
00
00
02
03
04
05
01
01
02
03
04
05
70
...
...
N
0
1
2
1
2
3
SC
0F
0F
12
10
08
04
02
01
12
10
09
04
02
01
09
05
09
05
GPL1
C8
C8
0A
2A
C8
C8
1B
0E
1B
07
10
18
46
20
80
07
0F
35
SMSC SCH311X
GPL2
Datasheet
FF
FF
0C
F0
FF
FF
1B
2A
3A
09
19
30
87
32
50
36
54
74
ID