TQFP
PIN #
7
BUFFER
TYPE
NAME
nWrite
Data
SYMBOL
nWDATA
DESCRIPTION
O12/OD12 This active low high current driver provides the
encoded data to the disk drive. Each falling edge
causes a flux transition on the media.
9
5
nHead
Select
nHDSEL
nDIR
O12/OD12 This high current output selects the floppy disk side
for reading or writing. A logic “1” on this pin means
side 0 will be accessed, while a logic “0” means side 1
will be accessed.
O12/OD12 This high current low active output determines the
direction of the head movement. A logic “1” on this
pin means outward motion, while a logic “0” means
inward motion.
Direction
Control
6
nStep
Pulse
Disk
nSTEP
O12/OD12 This active low high current driver issues a low pulse
for each track-to-track movement of the head.
15
nDSKCHG
IS
This input senses that the drive door is open or that
the diskette has possibly been changed since the last
drive selection. This input is inverted and read via bit
7 of I/O address 3F7H. The nDSKCHG bit also
depends upon the state of the Force Disk Change
bits in the Force FDD Status Change configuration
register (see section CR17 on page 107).
Change
2, 1
nDrive
nDS0,1
O12/OD12 Active low outputs select drives 0-1.
Select 0,1
100, 3 nMotor On nMTR0, 1
0,1
O12/OD12 These active low outputs select motor drives 0-1.
99
Drive
Density 0
DRVDEN0
O12/OD12 Indicates the drive and media selected. Refer to
configuration registers CR03, CR0B, CR1F.
12
nWrite
Protected
nWRTPRT
IS
This active low Schmitt Trigger input senses from the
disk drive that a disk is write protected. Any write
command is ignored.
The nWRPRT bit also
depends upon the state of the Force Write Protect
bits in the Force FDD Status Change configuration
register (see section CR17 on page 107).
11
10
16
wTrack 00
nIndex
nTRK0
IS
IS
This active low Schmitt Trigger input senses from the
disk drive that the head is positioned over the
outermost track.
This active low Schmitt Trigger input senses from the
disk drive that the head is positioned over the
beginning of a track, as marked by an index hole.
nINDEX
Drive
Density 1
DRVDEN 1 O12/OD12 Indicates the drive and media selected. Refer to
configuration registers CR03, CR0B, CR1F.
SERIAL PORTS INTERFACE
86
87
Receive
Data 2
RXD2/IRRX
TXD2/IRTX
IS
Receiver serial data input for port 2. IR Receive Data
Transmit
Data 2
O12PD
Transmit serial data output for port 2. IR transmit
data.
(Note5)
Receive
Data 1
76
77
RXD1
TXD1
nRTS1
I
Receiver serial data input for port 1.
Transmit serial data output for port 1.
Transmit
Data 1
O12
O6
79,89 nRequest
to Send
Active low Request to Send outputs for the Serial
Port. Handshake output signal notifies modem that
the UART is ready to transmit data. This signal can
be programmed by writing to bit 1 of the Modem
Control Register (MCR). The hardware reset will
reset the nRTS signal to inactive mode (high). nRTS
is forced inactive during loop mode operation.
nRTS2
(SYSOPT)
(System
Option)
At the trailing edge of hardware reset the nRTS2
inputs is latched to determine the configuration base
address: 0 = INDEX Base I/O Address 3F0 Hex; 1 =
INDEX Base I/O Address 370 Hex.
SMSC DS – FDC37N769
Page 9 of 137
Rev. 02-16-07
DATASHEET
SMSC [ SMSC CORPORATION ]
