IEEE 1284-B Connector PinOut

The Original IBM PC Parallel Port Pin-Out [also known now as the 'A' connector], was replaced by IEEE-1284 cable [25 Pin D-Sub on the Host side].
The IEEE-1284 'A' cable is backwards compatible with the original IBM Personal Computer [PC] Parallel Port cable and has the same pinout.
The IEEE-1284-B connector is designed to replace the Centronics pinout
The IEEE 1284-B: connector is a Female 36 pin ribbon connector (.0850 center line) Centronics, Bale locks [Peripheral connector, Printer side].
The IEEE-1284 'B' cable pin-out or signal assignments are shown below, along with the connector pin locations.

Pinout for a 36-pin male and female centronics connector
36-pin Centronic Connector

36 Pin Centronics Connector PinOut
Pin Number Signal name Pin Description and Function
1 nStrobe Strobe
2 data0 Address, Data Bit 0
3 data1 Address, Data Bit 1
4 data2 Address, Data Bit 2
5 data3 Address, Data Bit 3
6 data4 Address, Data Bit 4
7 data5 Address, Data Bit 5
8 data6 Address, Data Bit 6
9 data7 Address, Data Bit 7
10 /nAck Acknowledge
11 Busy Busy
12 PError Paper End
13 Select Select
14 /nAutoFd Autofeed
15 GND Signal Ground
16 GND Logic Ground
17 GND Chassis Ground
18 PLH Peripheral Logic High
19 GND Signal pin 1 GND
20 GND Signal pin 2 GND
21 GND Signal pin 3 GND
22 GND Signal pin 4 GND
23 GND Signal pin 5 GND
24 GND Signal pin 6 GND
25 GND Signal pin 7 GND
26 GND Signal pin 8 GND
27 GND Signal pin 9 GND
28 GND Signal pins 10, 12, 13 GND
29 GND Signal pin 11, 32 GND
30 GND Signal pins 14, 31, 36 GND
31 /nInit Initialize
32 /nFault Error
33 GND Signal Ground
34 GND Signal Ground
35 GND Signal Ground
36 /nSelectIn Select In

Personal Computer [PC] Parallel printer bus specification defines a Point-To-Point asynchronous bi-directional interface. Devices may be either 1284 compatible {the older parallel port devices} or 1284 compliant. The maximum recommended length for a printer cable is 25 feet. Centronics parallel cables run out to 12 feet. The IEEE1284 cable replaced the 'Centronics' cable, the Centronics cable is obsolete. Operates in five different modes: [The connector or cable does not change with each different mode, but the function of some of the pins do]

Compatibility mode; Centronics type operation (PC to Peripheral), providing the original (required) control signaling bits. These bits include 8 data lines, a Strobe, a Busy, an Acknowledge, a Select, Paper Empty, Fault, Initialize Printer, Select Printer, and a Auto Feed line. Compatibility mode is the basic mode of operation, asynchronous, byte wide operation with a transfer rate of between 50kBps to 150kBps.

Nibble mode; 4 bit data bus (Peripheral to PC), 8 bit data bus (PC to Peripheral); supporting uni-directional printer interfaces. This provides an interface which operates full speed forward and half speed in reverse. The transfer rate is between 50kBps to 150kBps

Byte mode; 8 bit bi-directional bus. Normal port operation. The transfer rate is between 50kBps to 150kBps

ECP; Extended Capabilities Port. Allowed the PC to send 32 bit data to the port, than letting the port divide up the data into four 8 byte messages, improving system (PC) operation. Transfer speeds are ten times faster then the previous modes.

EPP; Enhanced Parallel Port; Allows high-speed transfers of bytes in either direction. EPP is used with real time controlled peripherals. EPP transfer times are the same as ECP transfer rates.

IEEE-1284 'B' Connector, Signals in all Modes
Pin Compatibility mode Nibble mode Byte mode EPP mode ECP mode
1 nStrobe HostClk HostClk nWrite HostClk
2 Data 1 Data 1 Data 1 AD1 Data 1
3 Data 2 Data 2 Data 2 AD2 Data 2
4 Data 3 Data 3 Data 3 AD3 Data 3
5 Data 4 Data 4 Data 4 AD4 Data 4
6 Data 5 Data 5 Data 5 AD5 Data 5
7 Data 6 Data 6 Data 6 AD6 Data 6
8 Data 7 Data 7 Data 7 AD7 Data 7
9 Data 8 Data 8 Data 8 AD8 Data8
10 nAck PtrClk PtrClk Intr PeriphClk
11 Busy PtrBusy PtrBusy nWait PeriphAck
12 PError AckDataReq AckDataReq User defined 1 nAckReverse
13 Select Xflag Xflag User defined 3 Xflag
14 nAutoFd HostBusy HostBusy nDStrb HostAck
15 Signal Ground - - - -
16 Logic Ground
17 Chassis Ground
18 Peripheral Logic High
19 (nStrobe)ground return
20 (Data 1)ground return
21 (Data 2)ground return
22 (Data 3)ground return
23 (Data 4) ground return
24 (Data 5) ground return
25 (Data 6) ground return
26 (Data 7) ground return
27 (Data 8) ground return
28 (nACK, PError, Select) ground return
29 (Busy, nFault) ground return
30 (nAutoFd, nSelectIn, nInit) ground return
31 nInit nInit nInit nInit nReverseRequest
32 nFault nDataAvail nDataAvail User Defined 2 nPeriphRequest
33 Ground --
34 Ground --
35 Ground --
36 nSelectIn 1284 Active 1284 Active nAStrb 1284 Active

Back to the main IEEE-1284 bus page.

Parallel Cable Port Pinout .... Centronics Cable Pin-out .... 1284-A Cable Pinout .... 1284-C Cable Pinout

IEEE1284-A to 1284-B Adaptor Pinout .. IEEE1284-A to 1284-C Adaptor Pinout .. IEEE1284-B to 1284-C Adaptor Pinout

Pinout for a 36-pin male and female centronics connector
Centronic Connector Signal Assignments

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Modified 3/05/12
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