IEEE1284-C PinOut

The IEEE-1284 'C' cable pinout is shown below.
The connector for IEEE-1284C is a Male Mini Centronics [MDR36] 36 pin connector.
The C-style connector is one of three defined by the IEEE-1284 interface.
Each of the other physical interfaces are linked to after the pinout table.
The signal assignments for IEEE-1284-C are shown below.

26 pin MDR connector
MDR Style Connector

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

Personal Computer [PC] Parallel printer bus specification defines a Point-To-Point asynchronous bi-directional interface. Devices may be either 1284 compatible {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 maximum. The IEEE1284 cable replaced the 'Centronics' cable, the Centronics interface is obsolete. IEEE1284 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.
Note; the mode of operation changes the function of the signals, not the ground lines which are the same regardless of the mode being used.

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

The main IEEE-1284 bus page explains more about the interface.
Much of the IEEE-1284 electrical interface is not copied on each of the different styles pin outs, and not shown here.
The determining factor in using a particular connector defined by IEEE-1284 is determined by the gear that is already being used.

The links below point to the other pages related to the IEEE-1284 cable.
In each case these interfaces should not be used unless required, because they are out-dated.
The IEEE-1284 cable standard is stable and is no longer supported by a standards body, that is no updates are expected.
Many companies keep computer equipment until it can no longer be used or functions, so the IEEE-1284 still resides on a vast number of PC components.
The point, is to not upgrade to a system that has this style connector unless it's required to connect to some other pre-existing peripheral device.
In other words the IEEE-1284 connector is obsolete. A new PC will not have a IEEE-1284 connector, while a pre-installed working printer may.
It is not worth trying to get a PC vendor to install a IEEE-1284 connector to interface to a six year old printer.
Look instead to purchasing a new printer or using a USB to IEEE-1284 adaptor to make the PC to printer connection.
The USB to IEEE-1284 adaptor is the best upgrade option, and cheaper than buying a new printer.

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

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

In any case regardless of the IEEE-1284 interface being used, the standard is obsolete.
The data is listed here to assist in any attempted debug of an interface that is no longer functioning.
The electrical portion of the interface is simple TTL logic, and along with the connector has a low pin count.
However if the fault resides in the controller portion of the circuit than debugging may be a bit more difficult to repair.
This text only describes the portion of the circuit that drives the interface, not the processor that controls the entire device.
The reader should review both the main IEEE-1284 page and the related sub-pages, as possible suggestions are not re-listed on each topic.

Navigation: Engineering Home > Interface Buses > Cabled Interface Standards > IEEE-1284 Standard > C-Cable Variation.

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Modified 3/05/12
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