FDC37N869 View Datasheet(PDF) - SMSC -> Microchip
Part Name
Description
MFG CO.
FDC37N869
SMSC -> Microchip
'FDC37N869' PDF : 147 Pages View PDF
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 41 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.
Table 40 - FORMAT FIELDS
SYSTEM 34 (DOUBLE DENSITY) FORMAT
DATA
GAP4 SYN IAM GAP SYN IDAM C H S N C GAP SYN AM
C
aC
1C
YD E OR 2 C
DATA R GAP3 GAP
80x 12x
50x 12x
L C C 22x 12x
C
4b
4E 00
4E 00
4E 00
3x FC
3x FE
3x FB
C
A1
A1 F8
2
GAP4 SYN
aC
40x 6x
FF 00
SYSTEM 3740 (SINGLE DENSITY) FORMAT
DATA
IAM GAP SYN IDAM C H S N C GAP SYN AM
C
1C
YD E OR 2 C
DATA R GAP3 GAP
26x 6x
L C C 11x 6x
C
4b
FF 00
FF 00
FC
FE
FB or
F8
PERPENDICULAR FORMAT
DATA
GAP4 SYN IAM GAP SYN IDAM C H S N C GAP SYN AM
C
aC
1C
YD E OR 2 C
DATA R GAP3 GAP
80x 12x
50x 12x
L C C 41x 12x
C
4b
4E 00
4E 00
4E 00
3x FC
3x FE
3x FB
C
A1
A1 F8
2
SMSC DS – FDC37N869
Page 51
Rev. 11/09/2000
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