PARALLEL PORT PIN SIGNALS
510
Parallel port pin signals

This table shows the parallel port’s connected pins; other pins are not connected.

Parallel port signals
Pin Signal mode names:
Compatibility/Nibble Return
pin Signal
source Description
1 Busy/PtrBusy 19 Printer ■C mode: Positive true = not ready for data
■N mode: Data bits 3 then 7, then busy
status
2 Select/Xflag 20 Printer ■C mode: Positive true = online
■N mode: Data bits 1 then 5
3 nAck/PtrClk 21 Printer ■C mode: Negative true = data transfer
acknowledge
■N mode: Data qualifier
4 nFault/nDataAvail 22 Printer ■C mode: Negative true = printer fault exists
that prevents printing
■N mode: Negative low = data ready, then
data bits 0 then 4
5 PError/AckDataReq 23 Printer ■C mode: Positive true = printer error exists,
such as media tray empty
■N mode: Data bits 2 then 6