FDC37C78-HT Standard Microsystems (SMSC), FDC37C78-HT Datasheet - Page 44

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

Specifications of FDC37C78-HT

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

DATA TRANSFER COMMANDS
All of the Read Data, Write Data and Verify type
commands use the same parameter bytes and
return the same results information, the only
difference being the coding of bits 0-4 in the first
byte.
An implied seek will be executed if the feature was
enabled by the Configure command. This seek is
completely transparent to the user.
Busy bit for the drive will go active in the Main
Status Register during the seek portion of the
command.
reflected in the results status normally returned for
a Read/Write Data command. Status Register 0
(ST0) would contain the error code and C would
contain the cylinder on which the seek failed.
Read Data
A set of nine (9) bytes is required to place the FDC
in the Read Data Mode.
command has been issued, the FDC loads the
head (if it is in the unloaded state), waits the
specified head settling time (defined in the Specify
command), and begins reading ID Address Marks
and ID fields. When the sector address read off
the diskette matches with the sector address
specified in the command, the FDC reads the
sector's data field and transfers the data to the
FIFO.
After completion of the read operation from the
current sector, the sector address is incremented
by one and the data from the next logical sector is
read and output via the FIFO. This continuous
read
Operation". Upon receipt of TC, or an implied TC
(FIFO overrun/underrun), the FDC stops sending
data but will continue to read data from the current
sector, check the CRC bytes, and at the end of the
sector, terminate the Read Data Command.
function
If the seek portion fails, it will be
is
called
After the Read Data
"Multi-Sector
The Drive
Read
44
N determines the number of bytes per sector (see
Table 22 below). If N is set to zero, the sector size
is set to 128.
number of bytes to be transferred. If DTL is less
than 128, the FDC transfers the specified number
of bytes to the host. For reads, it continues to
read the entire 128-byte sector and checks for
CRC errors. For 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 21.
00
01
02
03
07
N
..
Table 20 - Sector Sizes
The DTL value determines the
SECTOR SIZE
1024 bytes
16 Kbytes
128 bytes
256 bytes
512 bytes
...