ST78C34 Exar Corporation, ST78C34 Datasheet - Page 5

• Manufacturer Part Number: ST78C34
• Description: General Purpose Parallel Printer Port With 83 Byte Fifo
• Manufacturer: Exar Corporation

SYMBOL DESCRIPTION
GND
RESET
-STROBE
-AUTOFDXT
INIT
-SLCTIN
GND
PD0-PD7
A0-A1
-IOW
-IOR
VCC
Symbol
Rev. 3.00
27-34
36-37
20
21
22
23
24
25
26
39
40
38
40
Pin
31-38
40-41
44
23
24
25
26
27
28
30
42
43
44
Signal
type
I/O
I/O
I/O
I/O
I/O
O
O
I
I
I
I
I
General purpose I/O or strobe output (open drain active low, with
General purpose I/O or line printer auto feed (open drain active
Signal and power ground.
Master reset (active high). A high on this pin will reset all the
outputs and internal registers.
internal pull-up). To transfer latched data to the external peripheral
or printer.
low, with internal pull-up). To signal the printer for continuous form
feed.
General purpose I/O or line printer initialize (open drain active
high, with internal pull-up). To signal the line printer to enter
internal initialization routine.
General purpose I/O or line printer select (open drain active low,
with internal pull-up). To select the line printer.
Power and signal ground.
of the ST78C34 parallel port. PD7-PD0 are latched during output
mode.
Write strobe (active low). A low on this pin will transfer the contents
of the CPU data bus to the addressed register.
Read strobe (active low). A low level on this pin transfers the
contents of the ST78C34 data bus to the CPU.
Power supply input.
Bi-directional parallel ports (three state). To transfer data in or out
Address lines. To select internal registers.
6-7
Pin Description
ST78C34