FDC37M607 datasheet(65/182 Pages) SMSC

65 / 182 page

Table 30 - Effects of WGATE and GAP Bits

WGATE

GAP

MODE

LENGTH OF

GAP2 FORMAT

FIELD

PORTION OF

GAP 2 WRITTEN

BY WRITE DATA

OPERATION

Conventional

Perpendicular

(500 Kbps)

Reserved

(Conventional)

Perpendicular

(1 Mbps)

22 Bytes

41 Bytes

0 Bytes

19 Bytes

0 Bytes

38 Bytes

LOCK

In order to protect systems with long DMA

latencies against older application software that

can disable the FIFO the LOCK Command has

been added.

This command should only be

used by the FDC routines, and application

software should refrain from using it.

If an

application calls for the FIFO to be disabled

then the CONFIGURE command should be

used.

The LOCK command defines whether the

EFIFO, FIFOTHR, and PRETRK parameters of

the CONFIGURE command can be RESET by

the DOR and DSR registers. When the LOCK

bit is set to logic "1" all subsequent "software

RESETS by the DOR and DSR registers will not

change the previously set parameters to their

default values. All "hardware" RESET from the

RESET pin will set the LOCK bit to logic "0" and

return the EFIFO, FIFOTHR, and PRETRK to

their default values.

A status byte is returned

immediately after issuing a a LOCK command.

This byte reflects the value of the LOCK bit set

by the command byte.

ENHANCED DUMPREG

The

DUMPREG

command

designed

support

system

run-time

diagnostics

and

application software development and debug.

To accommodate the LOCK command and the

enhanced PERPENDICULAR MODE command

the eighth byte of the DUMPREG command has

been modified to contain the additional data

from these two commands.

COMPATIBILITY

The FDC37M60x was designed with software

compatibility in mind.

It is a fully backwards-

compatible solution with the older generation

765A/B

disk

controllers.

The

FDC

also

implements on-board registers for compatibility

with the PS/2, as well as PC/AT and PC/XT,

floppy

disk

controller

subsystems.

After

hardware reset of the FDC, all registers,

functions and enhancements default to a PC/AT,

PS/2 or PS/2 Model 30 compatible operating

mode, depending on how the IDENT and MFM

bits are configured by the system BIOS.

FDC37M607 Datasheet(PDF) 65 Page - SMSC Corporation

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