IEEE1284-A to IEEE1284-B Adaptor Pin-Out

This page defines an intermediate interface to bridge the gap during the transition from Centronics obsolescence to IEEE1284 adoption.
The IEEE-1284 interface is defined in the IEEE standard and is a better made cable than the older Centronics interface it replaced, and the original parallel port cable had no specification at all. The IEEE-1284 interface defined three different connector styles; A, B, and C.

The IEEE-1284 'A' connector defines a 25-pin D-Sub connector.
The IEEE 1284-B connector is designed to replace the Centronics connector. The IEEE 1284-B: connector is a Female 36 pin ribbon connector (.0850 center line) Centronics, Bale locks [Peripheral connector, Printer side].
The Original IBM PC [LPT] Parallel Port Pin-Out is defined as the 'A' connector in the IEEE1284 interface.

**IEEE 1284-A to 1284-B Adapter PinOut**
Host A connector	Function	Peripheral B connector
1	nStrobe	1
2	Data bit 1	2
3	Data bit 2	3
4	Data bit 3	4
5	Data bit 4	5
6	Data bit 5	6
7	Data bit 6	7
8	Data bit 7	8
9	Data bit 8	9
10	nAck	10
11	Busy	11
12	PError	12
13	Select	13
14	nAutoFd	14
15	nFault	32
16	nInit	31
17	nSelectIn	36
18	Pin 1 (nStrobe) ground return	19
19	(Data 1 and 2) ground return	20, 21
20	(Data 3 and 4) ground return	22, 23
21	(Data 5 and 6) ground return	24, 25
22	(Data 7 and 8) ground return	26, 27
23	Pins 11 and 15 ground return	29
24	Pins 10, 12, and 13 ground return	28
25	Pins 14, 16, and 17 ground return	30

The 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 The IEEE1284 cable replaced the 'Centronics' cable which is obsolete.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}

Engineering 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, Assignment, Specification, Standard, Defined, Constraint, Properties, Lines, Data, Labels, Adaptor, LPT Port


Home


Distributors	Components	Equipment	Software	Standards	Buses	Design	Reference