FDC37C672QFP SMSC Corporation, FDC37C672QFP Datasheet - Page 54

• Manufacturer Part Number: FDC37C672QFP
• Description: ENHANCED SUPER I/O CONTROLLER WITH FAST IR
• Manufacturer: SMSC Corporation

8.1.7
SMSC FDC37C672
GAP4a
GAP4a
GAP4a
80x
40x
80x
Format A Track
The Format command allows an entire track to be formatted. After a pulse from the IDX pin is detected,
the FDC starts writing data on the disk including gaps, address marks, ID fields, and data fields per the
IBM System 34 or 3740 format (MFM or FM respectively). The particular values that will be written to the
gap and data field are controlled by the values programmed into N, SC, GPL, and D which are specified by
the host during the command phase. The data field of the sector is filled with the data byte specified by D.
The ID field for each sector is supplied by the host; that is, four data bytes per sector are needed by the
FDC for C, H, R, and N (cylinder, head, sector number and sector size respectively).
After formatting each sector, the host must send new values for C, H, R and N to the FDC for the next
sector on the track. The R value (sector number) is the only value that must be changed by the host after
each sector is formatted. This allows the disk to be formatted with nonsequential sector addresses
(interleaving). This incrementing and formatting continues for the whole track until the FDC encounters a
pulse on the IDX pin again and it terminates the command.
Table 8.7 contains typical values for gap fields which are dependent upon the size of the sector and the
number of sectors on each track. Actual values can vary due to drive electronics.
4E
FF
4E
SYNC
SYNC
SYNC
12x
12x
00
6x
00
00
C2
C2
3x
3x
IAM
IAM
IAM
FC
FC
FC
GAP1
GAP1
GAP1
50x
26x
50x
4E
FF
4E
SYSTEM 3740 (SINGLE DENSITY) FORMAT
SYSTEM 34 (DOUBLE DENSITY) FORMAT
SYNC
SYNC
SYNC
12x
12x
00
00
00
6x
A1
A1
3x
3x
IDAM
IDAM
PERPENDICULAR FORMAT
IDAM
DATASHEET
FE
Table 8.7 - Format Fields
FE
FE
C
C
C
Y
L
Y
L
Y
L
H
D
H
D
H
D
Page 54
S
E
C
S
E
C
S
E
C
N
O
N
O
N
O
C
R
C
C
R
C
C
R
C
GAP2
GAP2
GAP2
22x
11x
41x
4E
FF
4E
SYNC
SYNC
SYNC
12x
12x
00
6x
00
00
A1
A1
3x
3x
DATA
DATA
DATA
FB or
AM
AM
AM
F8
FB
FB
F8
F8
Enhanced Super I/O Controller with Fast IR
DATA
DATA
DATA
C
R
C
C
R
C
C
R
C
GAP3 GAP 4b
GAP3 GAP 4b
GAP3 GAP 4b
Rev. 10-29-03
Datasheet