The IEEE-1284 'A' cable is backwards compatible with the IBM Personal
Computer [PC] Parallel Port cable [Centronics Connector] and has the same pinout listed in column 1 . The IEEE-1284 'C' cable
pin-out assignments are shown in column 3. The connector for IEEE-1284 'A' is a 25 Pin D-Sub while the connector for IEEE-1284 'C' is a Male Mini
Centronics [MDR36] 36 pin connector. This adaptor cable is used to interconnect a device with an 'A' connector with one that uses a 'C' connector
The Original IBM PC Parallel Port, also called the LPT port [defined as the IEEE-1284 'A' cable], was replaced by the IEEE-1284 standard, and is a better made cable.
| Host A connector | Function | Peripheral C connector |
| 1 | nStrobe | 15 |
| 2 | Data bit 1 | 6 |
| 3 | Data bit 2 | 7 |
| 4 | Data bit 3 | 8 |
| 5 | Data bit 4 | 9 |
| 6 | Data bit 5 | 10 |
| 7 | Data bit 6 | 11 |
| 8 | Data bit 7 | 12 |
| 9 | Data bit 8 | 13 |
| 10 | nAck | 3 |
| 11 | Busy | 1 |
| 12 | PError | 5 |
| 13 | Select | 2 |
| 14 | nAutoFd | 17 |
| 15 | nFault | 4 |
| 16 | nInit | 14 |
| 17 | nSelectIn | 16 |
| 18 | Pin 1 (nStrobe) ground return | 33 |
| 19 | Pins 2 and 3 (Data 1 and 2) ground return | 24, 25 |
| 20 | Pins 4 and 5 (Data 3 and 4) ground return | 26, 27 |
| 21 | Pins 6 and 7 (Data 5 and 6) ground return | 28, 29 |
| 22 | Pins 8 and 9 (Data 7 and 8) ground return | 30, 31 |
| 23 | Pins 11 and 15 ground return | 19 and 22 |
| 24 | Pins 10, 12, and 13 ground return | 20, 21, and 23 |
| 25 | Pins 14, 16, and 17 ground return | 32, 34, and 35 |
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replaced the 'Centronics' cable, the Centronics cable is obsolete.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, asychronous, 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.
Back to the main IEEE-1284 bus page. {This Web Site}
Centronics Connector
Pinout .. Parallel Port Connector
Pinout .. 1284-A Cable Pinout ..
1284-B Cable Pinout ..
1284-C Cable Pinout
{This Web Site}
Design Key words: IEEE-1284, Parallel printer bus specification, Peripheral Bus, Physical, Mechanical, Type, IEEE1284 Description, Brief, ICs, Integrated Circuits, Vendors, Products, Manufacturers, specification, Personal Computer, PC Bus pin out, 'A' Cable Pinout, Pin Out, Pins, Signals, Pin Number, LPT, Assignment, Specification, Standard, Defined, Constraint, Properties, Lines, Data, Labels, Adaptor
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