FDC37C78-HT Standard Microsystems (SMSC), FDC37C78-HT Datasheet - Page 49

• Manufacturer Part Number: FDC37C78-HT
• Manufacturer: Standard Microsystems (SMSC)

Specifications of FDC37C78-HT

• Package Type: TQFP
• Lead Free Status / RoHS Status: Compliant

Format A Track
The Format command allows an entire track to be
formatted.
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).
GAP4a
GAP4a
GAP4a
80x
40x
80x
4E
FF
4E
SYNC
SYNC
SYNC
12x
12x
00
6x
00
00
After a pulse from the IDX pin is
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
FE
FE
FE
FORMAT FIELDS
C
Y
C
Y
C
Y
L
L
L
H
D
H
D
H
D
S
E
C
S
E
C
S
E
C
49
N
O
N
O
N
O
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.
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 28 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.
C
R
C
C
R
C
C
R
C
GAP2
GAP2
GAP2
22x
11x
41x
4E
FF
4E
SYNC
SYNC
SYNC
12x
12x
00
00
00
6x
A1
A1
3x
3x
DATA
DATA
DATA
FB or
AM
AM
AM
F8
FB
F8
FB
F8
DATA
DATA
DATA
C
R
C
C
R
C
C
R
C
GAP3 GAP 4b
GAP3 GAP 4b
GAP3 GAP 4b
This