Parallel printer interface

The most common standard for parallel printer interfaces from the 1970s to the early 2000s was the "Centronics interface" originally defined by printer manufacturer Centronics, and widely employed throughout the industry.

It has a parallel, originally unidirectional, 8-bit data path, with a Strobe signal indicating new data, an ACK signal indicating data acceptance (often ignored), and a Ready signal indicating the printer can accept data.

Signal levels are 5 V TTL.

The original connector - almost always used on on the printer side - was a 36-pin micro-ribbon connector. On the computer side, a 25-pin Sub-D connector was the de-facto standard established with the IBM PC.