LPC47S457-NC SMSC [SMSC Corporation], LPC47S457-NC Datasheet - Page 52

• Manufacturer Part Number: LPC47S457-NC
• Description: Advanced I/O with X-Bus Interface
• Manufacturer: SMSC [SMSC Corporation]

writes, it completes the 128-byte sector by filling in zeros. If N is not set to 00 Hex, DTL should be set to FF Hex and
has no impact on the number of bytes transferred.
The amount of data which can be handled with a single command to the FDC depends upon MT (multi-track) and N
(number of bytes/sector).
The Multi-Track function (MT) allows the FDC to read data from both sides of the diskette. For a particular cylinder,
data will be transferred starting at Sector 1, Side 0 and completing the last sector of the same track at Side 1.
If the host terminates a read or write operation in the FDC, the ID information in the result phase is dependent upon
the state of the MT bit and EOT byte. Refer to Table 19.
At the completion of the Read Data command, the head is not unloaded until after the Head Unload Time Interval
(specified in the Specify command) has elapsed. If the host issues another command before the head unloads,
then the head settling time may be saved between subsequent reads.
If the FDC detects a pulse on the nINDEX pin twice without finding the specified sector (meaning that the diskette's
index hole passes through index detect logic in the drive twice), the FDC sets the IC code in Status Register 0 to "01"
indicating abnormal termination, sets the ND bit in Status Register 1 to "1" indicating a sector not found, and
terminates the Read Data Command.
After reading the ID and Data Fields in each sector, the FDC checks the CRC bytes. If a CRC error occurs in the ID
or data field, the FDC sets the IC code in Status Register 0 to "01" indicating abnormal termination, sets the DE bit
flag in Status Register 1 to "1", sets the DD bit in Status Register 2 to "1" if CRC is incorrect in the ID field, and
terminates the Read Data Command. Table 21 describes the effect of the SK bit on the Read Data command
execution and results. Except where noted in Table 20, the C or R value of the sector address is automatically
incremented (see Table 22).
SMSC DS – LPC47S45x
VALUE
SK BIT
0
0
Normal Data
Deleted Data
DATA ADDRESS
ENCOUNTERED
MARK TYPE
MT
0
1
0
1
0
1
N
1
1
2
2
3
3
256 x 26 = 6,656
256 x 52 = 13,312
512 x 15 = 7,680
512 x 30 = 15,360
1024 x 8 = 8,192
1024 x 16 = 16,384
SECTOR
MAXIMUM TRANSFER
READ?
Table 19 − Effects of MT and N Bits
Table 20 − Skip Bit vs Read Data Command
Yes
Yes
00
01
02
03
07
N
..
DATASHEET
CAPACITY
Table 18 − Sector Sizes
CM BIT OF
ST2 SET?
Page 52 of 259
Yes
No
SECTOR SIZE
1024 bytes
16 Kbytes
128 bytes
256 bytes
512 bytes
...
Normal termination.
Address not incremented. Next sector not
searched for.
26 at side 0 or 1
26 at side 1
15 at side 0 or 1
15 at side 1
8 at side 0 or 1
16 at side 1
FINAL SECTOR READ
RESULTS
FROM DISK
DESCRIPTION OF RESULTS
Rev. 07/09/2001