FDC37B77X SMSC Corporation, FDC37B77X Datasheet - Page 32

• Manufacturer Part Number: FDC37B77X
• Description: ENHANCED SUPER I/O CONTROLLER WITH WAKE UP FEATURES
• Manufacturer: SMSC Corporation

RESET
There are three sources of system reset on the
FDC: the RESET pin of the FDC, a reset
generated via a bit in the DOR, and a reset
generated via a bit in the DSR. At power on, a
Power On Reset initializes the FDC. All resets
take the FDC out of the power down state.
All operations are terminated upon a RESET,
and the FDC enters an idle state. A reset while
a disk write is in progress will corrupt the data
and CRC.
On exiting the reset state, various internal
registers are cleared, including the Configure
command information, and the FDC waits for a
new command. Drive polling will start unless
disabled by a new Configure command.
RESET Pin (Hardware Reset)
The RESET pin is a global reset and clears all
registers except those programmed by the
Specify command.
enabled and must be cleared by the host to exit
the reset state.
BIT NO.
1,0
7
6
5
4
3
2
WP
T0
HD
DS1,0
SYMBOL
The DOR reset bit is
Write
Protected
Track 0
Head
Address
Drive Select
NAME
Table 16- Status Register 3
Unused. This bit is always "0".
Indicates the status of the WP pin.
Unused. This bit is always "1".
Indicates the status of the TRK0 pin.
Unused. This bit is always "1".
Indicates the status of the HDSEL pin.
Indicates the status of the DS1, DS0 pins.
32
DOR Reset vs. DSR Reset (Software Reset)
These two resets are functionally the same.
Both will reset the FDC core, which affects drive
status information and the FIFO circuits. The
DSR reset clears itself automatically while the
DOR reset requires the host to manually clear it.
DOR reset has precedence over the DSR reset.
The DOR reset is set automatically upon a pin
reset. The user must manually clear this reset
bit in the DOR to exit the reset state.
MODES OF OPERATION
The FDC has three modes of operation, PC/AT
mode, PS/2 mode and Model 30 mode. These
are determined by the state of the IDENT and
MFM bits 6 and 5 respectively of CRxx.
PC/AT mode - (IDENT high, MFM a "don't
care")
The PC/AT register set is enabled, the DMA
enable bit of the DOR becomes valid (FINTR
and DRQ can be hi Z), and TC and DENSEL
become active high signals.
DESCRIPTION