37C672 datasheet(49/173 Pages) SMSC

49 / 173 page

Enhanced Super I/O Controller with Fast IR

Datasheet

SMSC FDC37C672

Page 49

Rev. 10-29-03

PRELIMINARY DATASHEET

INVALID CODES

DATA BUS

PHASE

R/W

REMARKS

Command

───── Invalid Codes ─────

Invalid Command Codes (NoOp -

FDC goes into Standby State)

Result

─────── ST0 ───────

ST0 = 80H

LOCK

DATA BUS

PHASE

R/W

REMARKS

Command

LOCK

Command Codes

Result

LOCK

SC is returned if the last command that was issued was the Format command. EOT is returned if the last

command was a Read or Write.

Note:

These bits are used internally only. They are not reflected in the Drive Select pins. It is the user's

responsibility to maintain correspondence between these bits and the Drive Select pins (DOR).

8.1

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. The Drive Busy bit for the drive will go active in the Main Status

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.

8.1.1

Read Data

A set of nine (9) bytes is required to place the FDC in the Read Data Mode. After the Read Data

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 function is

called "Multi-Sector 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.

N determines the number of bytes per sector (see Table 8.1 below). If N is set to zero, the sector size is

set to 128. The DTL value determines the 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.

37C672 Datasheet(PDF) 49 Page - SMSC Corporation

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