FDC37B78X View Datasheet(PDF) - SMSC -> Microchip

Part Name

Description

Manufacturer

FDC37B78X

Enhanced Super I/O Controller with ACPI Support, Real Time Clock and Consumer IR

SMSC -> Microchip 

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 Register during the seek portion of

the command. If the seek portion fails, it is

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. 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 23 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.

TABLE 23 - SECTOR SIZES

N

SECTOR SIZE

00

128 bytes

01

256 bytes

02

512 bytes

03

1024 bytes

..

...

07

16 Kbytes

56

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