Parallel Interface; Serial Interface, Powered And Non-Powered - HP dx7400 - Microtower PC Service & Reference Manual

Parallel Interface

Connector and Icon
Pin Signal
1 Strobe
2 Data Bit 0
3 Data Bit 1
4 Data Bit 2
5 Data Bit 3
6 Data Bit 4
7 Data Bit 5
8 Data Bit 6
9 Data Bit 7

Serial Interface, Powered and Non-Powered

Connector and Icon
Pin Signal
10 Acknowledge
11 Busy
12 Paper End
13 Select
14 Auto Linefeed
15 Error
16 Initialize Printer
17 Select IN
18–25 Signal Ground
Pin Signal
1 Carrier Detect (12V if powered)
2 Receive Data
3 Transmit Data
4 Data Terminal Ready
5 Signal Ground
6 Data Set Ready
7 Request to Send
8 Clear to Send
9 Ring Indicator (5V if powered)
Parallel Interface 121