DESCRIPTION OF PIN FUNCTIONS
PIN NO.
38
NAME
Reset
SYMBOL
RESET
BUFFER
TYPE
IS
DESCRIPTION
This active high signal resets the chip and
must be valid for 500 ns minimum. The effect
on the internal registers is described in the
appropriate section.
The configuration
registers are not affected by this reset.
Raw serial bit stream from the disk drive, low
active. Each falling edge represents a flux
transition of the encoded data.
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.
Indicates the drive and media selected. Refer
to configuration registers CR03, CR0B,
CR1F.
Indicates whether a low (250/300 Kb/s) or
high (500 Kb/s) data rate has been selected.
This is determined by the IDENT bit in
Configuration Register 3.
FLOPPY DISK INTERFACE
21
Read Disk Data
nRDATA
IS
27
Write
Data
Head
Select
nWDATA
OD20
29
nHDSEL
OD20
33
Direction
Control
Step Pulse
nDIR
OD20
31
nSTEP
OD20
20
Disk Change
nDSKCHG
IS
22,
23
24
DRVDEN 0,
DRVDEN 1
Density Select
DRVDEN0,
DRVDEN1
DENSEL
OD20
OD20
7
SMSC [ SMSC CORPORATION ]
