5
PIN DESCRIPTIONS
BUFFER
TYPE
PIN NO.
NAME
SYMBOL
DESCRIPTION
FLOPPY DISK INTERFACE
IS Raw serial bit stream from the disk drive, low
active. Each falling edge represents a flux
transition of the encoded data.
75
Read Disk
Data
nRDATA
nWDATA
69
71
Write
Data
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. This pin is
high impedance when nRESET is active low.
Head
nHDSEL
nDIR
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. . This pin is high
impedance when nRESET is active low.
Select
67
68
Direction
Control
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. This pin is high impedance when
nRESET is active low.
Step Pulse
nSTEP
OD12 This active low high current driver issues a low
pulse for each track-to-track movement of the
head. This pin is high impedance when nRESET is
active low.
76
63
Disk Change nDSKCHG
IS
This input senses that the drive door is open or
that the diskette has possibly been changed since
the last drive selection.
DRVDEN 0
DRVDEN 0
OD12 An active low on this pin indicates a disk drive
spindle speed change from 300 RPM to 360 RPM
or 1.2M format disks in three mode drives. This
pin should be tied to the disk drives spindle speed
control input pin. This pin is high impedance when
nRESET is active low.
77
70
DRVDEN 1
Write Gate
DRVDEN1
nWGATE
OD12 Reserved for future use.
OD12 This active low high current driver allows current to
flow through the write head. It becomes active just
prior to writing to the diskette. This pin is high
impedance when nRESET is active low.
73
72
74
64
65
Track 0
Index
nTRK0
IS
IS
IS
This active low Schmitt Trigger input senses from
the disk drive that the head is positioned over the
outermost track.
nINDEX
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.
Write Protect nWRTPRT
This active low Schmitt Trigger input senses from
the disk drive that a disk is write protected. Any
write command is ignored.
Motor On 0
nMTR0
OD12 This active low open drain output selects motor
drive 0. This pin is high impedance when nRESET
is active low.
Drive Select 0 nDS0
OD12 This active low open drain output selects drive 0.
This pin is high impedance when nRESET is active
low.
SMSC DS – USB97CFDC2-01
Page 8
Rev. 02-27-07
DATASHEET
SMSC [ SMSC CORPORATION ]
