Appendixes
55
Interfaces
Parallel Interface
Specifications
Transmission mode
8-bit parallel data
Receive buffer size
16K bytes
Transmission modes
Compatible mode
It is an asynchronous forward direction of the byte
width (from host to printer) channel, and the interface
line of the data is operated in accordance with signal
line definitions of Centronics.
NIBBLE mode
Nibble mode is asynchronous reverse channel
communication with data transmission controlled by
the host computer. In reverse channel transmission, the
data is nibble transmitted in two parts using four status
lines (Fault, Select, PE, and Busy). And nibble mode can
be used along with compatible mode to send data in
two directions.
ECP mode
ECP mode permits bi-directional asynchronous data
transmission, and thanks to its interlock handshake, it
does not require the timing necessary with compatible
mode.
Signal level
IEEE1284 standard
Signal line and pin assignment table
Pin No.
Signal name
I/O
Function
1
*STROBE
Input
Strobe signal to read in 8-bit data
2-9
DATA1-8
Input
8-bit parallel signal
10
*ACKNLG
Output
8-bit data request signal
11
BUSY
Output
Signal specifying printer busy
12
PERROR
Output
Signal specifying media out
13
SELECT
Output
Signal specifying if the printer is on-line
(printing enabled) or off-line (pausing)
14
AUTOFD
Input
Invalid (ignored)
15
NC
------
Not used
16
GND
------
Signal ground
17
FGND
------
Frame ground
18
P.L.H
Output
Peripheral logic high (pull up to +5V at
1k
Ω
)
19-30
GND
------
Ground for twisted pair return
31
*INIT
Input
Printer reset
32
*FAULT
Output
Signal specifying printer error
33-35
NC
------
Not used
36
SELECTIN
Input
Invalid (ignored)
