GM82C803CN Datasheet, PDF (50/84 Pages) List of Unclassifed Manufacturers – 2.88 MB FDC/ Dual UARTs with FIFO/PIO(EPP/ ECP)/ IDE Interface/ S-IR/ PnP

GM82C803CN
Format a Track
The Format command allows an entire track to be formatted. After the index hole is detected, data is written on the disk-
ette; 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 sectors is supplied by the Host; that is, four data bytes per sector are needed by
the FDC for C, H, R and N.
After formatting each sector, the host must send new values for C, H, R and N to the FDC for the next 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 index hole for the second time and it terminates the command.
Table 4-24. 4-25 shows the relationship between N, SC and GPL, for various sector sizes.
Table 4-24. Typical Values for Formatting
Mode
125 Kbps
FM
250 Kbps
MFM***
250 Kbps
FM
500 Kbps
MFM***
Sector Size
decimal
128
128
256
512
1024
2048
256
256
512
512
1024
2048
4096
128
256
512
1024
2048
4096
256
512
512
1024
2048
4096
8192
Sector Code
hex
0
0
1
2
3
4
1
1
2
2
3
4
5
0
1
2
3
4
5
1
2
2
3
4
5
6
EOT
hex
12
10
8
4
22
1
12
10
8
9
4
2
1
1A
F
8
4
2
1
1A
F
12
8
4
2
1
Sector Gap*
hex
7
10
18
46
C8
C8
A
20
2A
2A
80
C8
C8
7
B
1B
47
C8
C8
E
1B
1B
35
99
C8
C8
Format GAP3**
hex
9
19
30
87
FF
FF
C
32
50
50
F0
FF
FF
1B
2A
3A
8A
FF
FF
36
54
6C
74
FF
FF
FF
* : Suggested values of GPL in Read or Write commands to avoid splice point between data field and ID field of
contiguous sections
** : Suggested values of GPL in format command
*** : In MFM mode. FDC cannot perform a Read/Write/Format operation with 128 bytes/sector (N=0)