TQFP
PIN #
7
9
NAME
nWrite
Data
nHead
Select
Direction
Control
nStep
Pulse
Disk
Change
SYMBOL
nWDATA
nHDSEL
BUFFER
TYPE
O12/OD12
O12/OD12
5
nDIR
O12/OD12
6
15
nSTEP
nDSKCHG
O12/OD12
IS
2, 1
100, 3
99
12
nDrive
Select 0,1
nMotor On
0,1
Drive
Density 0
nWrite
Protected
nDS0,1
nMTR0, 1
DRVDEN0
O12/OD12
O12/OD12
O12/OD12
DESCRIPTION
This active low high current driver provides the
encoded data to the disk drive. Each falling edge
causes a flux transition on the media.
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.
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.
This active low high current driver issues a low pulse
for each track-to-track movement of the head.
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 108).
Active low outputs select drives 0-1.
These active low outputs select motor drives 0-1.
11
10
16
wTrack 00
nIndex
Drive
Density 1
Receive
Data 2
Transmit
Data 2
(Note
5
)
Receive
Data 1
Transmit
Data 1
nRequest
to Send
(System
Option)
86
87
76
77
79,89
Indicates the drive and media selected. Refer to
configuration registers CR03, CR0B, CR1F.
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 108).
nTRK0
IS
This active low Schmitt Trigger input senses from the
disk drive that the head is positioned over the
outermost track.
nINDEX
IS
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.
DRVDEN 1 O12/OD12 Indicates the drive and media selected. Refer to
configuration registers CR03, CR0B, CR1F.
SERIAL PORTS INTERFACE
RXD2/IRRX
IS
Receiver serial data input for port 2. IR Receive Data
TXD2/IRTX
RXD1
TXD1
nRTS1
nRTS2
(SYSOPT)
O12PD
I
O12
O6
Transmit serial data output for port 2. IR transmit
data.
Receiver serial data input for port 1.
Transmit serial data output for port 1.
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.
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. 12/21/2000
SMSC [ SMSC CORPORATION ]
