FDC37B727-NS Standard Microsystems (SMSC), FDC37B727-NS Datasheet - Page 68

• Manufacturer Part Number: FDC37B727-NS
• Manufacturer: Standard Microsystems (SMSC)

Specifications of FDC37B727-NS

• Pin Count: 128
• Lead Free Status / RoHS Status: Compliant

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
LOCK command. This byte reflects the value of
the LOCK bit set by the command byte.
ENHANCED DUMPREG
The DUMPREG command is designed to support
system run-time diagnostics and application
software
development
and
debug.
To
68
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
This
compatibility in mind.
compatible solution with the older generation
765A/B
implements on-board registers for compatibility
with the PS/2, as well as PC/AT and PC/XT,
floppy disk controller subsystems. After a
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.
FORCE WRITE PROTECT
The Force Write Protect function forces the FDD
nWRTPRT input active if the FORCE WRTPRT
bit is active. The Force Write Protect function
applies to the nWRTPRT pin in the FDD
Interface as well as the nWRTPRT pin in the
Parallel Port FDC.
Register
chip
disk
L8CR_C5
was
controllers.
designed
for
It is a fully backwards-
Refer to Configuration
more
The
with
information.
FDC
software
also