Motorola MVME712AM 用户手册

Interconnect Signals

3-5

20

PRACK*

DATA ACKNOWLEDGE (Printer) - a low level 
input pulse indicating that the next character 
may be sent. 

21

PRPE

PAPER EMPTY (Printer) - out of paper. 

22

PRBSY

BUSY (Printer) - an input signal indicating that 
the printer cannot receive data. 

23

INPRIME*

INPUT PRIME (Printer) - an output signal that 
clears the printer buffer and initializes the logic. 

24

PRSEL

SELECTED (Printer) - an input signal indicating 
that the printer is selected. 

25

GND

GROUND 

26

PRFAULT*

FAULT (Printer) - an input signal that indicates 
a printer fault condition. 

27

GND

GROUND 

28

TXD3

TRANSMIT DATA (serial port 3) - data to be 
transmitted is furnished on this line to the 
modem from the terminal. 

29

GND

GROUND 

30

RXD3

RECEIVE DATA (serial port 3) - data that is 
demodulated from the receive line is presented 
to the terminal by the modem. 

31

CTS3

CLEAR TO SEND (serial port 3) - CTS is a 
function supplied to the terminal by the modem, 
and indicates that it is permissible to begin 
transmission of a message. When using a 
modem, CTS follows the off-to-on transition of 
RTS after a time delay. 

32

RTS3

REQUEST TO SEND (serial port 3) - RTS is 
supplied by the terminal to the modem when it 
is required to transmit a message. With RTS off, 
the modem carrier remains off. When RTS is 
turned on, the modem immediately turns on the 
carrier. 

33

DCD3

DATA CARRIER DETECT (serial port 3) - sent 
by the modem to the terminal to indicate that a 
valid carrier is being received.