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 

COMMAND SET/DESCRIPTIONS

Commands can be written whenever the FDC is

in the command phase. Each command has a

unique set of needed parameters and status

results. The FDC checks to see that the first

byte is a valid command and, if valid, proceeds

with the command. If it is invalid, an interrupt is

issued. The user sends a Sense Interrupt

Status command which returns an invalid

command error. Refer to TABLE 20 for

explanations of the various symbols used.

TABLE 21 lists the required parameters and the

results associated with each command that the

FDC is capable of performing.

SYMBOL

C

D

D0, D1

DIR

DS0, DS1

DTL

EC

EFIFO

EIS

EOT

GAP

GPL

TABLE 20 - DESCRIPTION OF COMMAND SYMBOLS

NAME

DESCRIPTION

Cylinder Address The currently selected address; 0 to 255.

Data Pattern

The pattern to be written in each sector data field during

formatting.

Drive Select 0-1

Designates which drives are perpendicular drives on the

Perpendicular Mode Command. A "1" indicates a perpendicular

drive.

Direction Control If this bit is 0, then the head will step out from the spindle during a

relative seek. If set to a 1, the head will step in toward the spindle.

Disk Drive Select

Special Sector

Size

DS1 DS0 Drive Selected

0 0 Drive 0

0 1 Drive 1

By setting N to zero (00), DTL may be used to control the number

of bytes transferred in disk read/write commands. The sector size

(N = 0) is set to 128. If the actual sector (on the diskette) is larger

than DTL, the remainder of the actual sector is read but is not

passed to the host during read commands; during write

commands, the remainder of the actual sector is written with all

zero bytes. The CRC check code is calculated with the actual

sector. When N is not zero, DTL has no meaning and should be

set to FF HEX.

Enable Count

When this bit is "1" the "DTL" parameter of the Verify command

becomes SC (number of sectors per track).

Enable FIFO

This active low bit when a 0, enables the FIFO. A "1" disables the

FIFO (default).

Enable Implied

Seek

When set, a seek operation will be performed before executing any

read or write command that requires the C parameter in the

command phase. A "0" disables the implied seek.

End of Track

The final sector number of the current track.

Alters Gap 2 length when using Perpendicular Mode.

Gap Length

The Gap 3 size. (Gap 3 is the space between sectors excluding

the VCO synchronization field).

41

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