DESCRIPTION OF PIN FUNCTIONS
BUFFER
QFP/
TQFP
PIN NO.
TYPE
NAME
Interrupt
Request
A, C, D,
E, F,
SYMBOL
DESCRIPTION
19,
IRQ_A
IRQ_C
IRQ_D
IRQ_E
IRQ_F
O24
The interrupt request from the logical device
or IRQIN is output on one of the IRQA-G
signals. Refer to the configuration registers
for more information.
37-40,
If EPP or ECP Mode is enabled, this output
is pulsed low, then released to allow sharing
of interrupts.
OD24
27
57
Chip Select Input nCS
I
When enabled, this active low pin serves as
an input for an external decoder circuit
which is used to qualify address lines above
A10.
Reset
RESET
IS
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.
FLOPPY DISK INTERFACE
16
10
nRead Disk Data nRDATA
IS
Raw serial bit stream from the disk drive,
low active. Each falling edge represents a
flux transition of the encoded data.
nWrite
Gate
nWGATE
nWDATA
nHDSEL
This active low high current driver allows
current to flow through the write head. It
becomes active just prior to writing to the
diskette.
OD48
9
nWrite
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.
OD48
OD48
11
nHead
Select
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 ac-
cessed.
7
SMSC [ SMSC CORPORATION ]
