IEEE-488 (GLIB)

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Date Published:	July 13, 2020
Last Modified:	July 13, 2020

Overview

IEEE-488 is a parallel 8-bit short-range multi-master communications bus. It is more commonly known as GPIB (General Purpose Interface Bus).

Property	Value
Serial/Parallel	Parallel
Drive Type	Single-ended
Num. Signal Lines	16 (8 data, 3 handshake, 5 bus management) + 8 GND
Duplexity	Full
Connection Topology	Multi-master, star or forked
Layers	Initially, only the physical and electrical layers were specified. The commands/message format varied between manufacturers or even between devices made by the same manufacturer. Later on standard commands were specified (IEEE 488.2)

History

In the late 1960’s, Hewlett-Packard developed the HP Interface Bus (HP-IB) to connect the automated test and measurement instruments they manufactured to computers and other controllers. HP licensed the HP-IB technology to other manufacturers, and as the bus became popular, it became known as the General Purpose Interface Bus (GPIB)¹.

In 1975 IEEE standardized the GPIB as Standard Digital Interface For Programmable Instrumentation (IEEE 488). In 1987 IEEE released 488.2 as Standard Codes, Formats, Protocols, and Common Commands which specified basic device-independent syntax and messages.

Although initially designed for connecting instrumentation to computers, in 1977 HP also used the GPIB bus inside it’s Commodore PET range of personal computers to connect peripherals¹. However this was quickly replaced with faster buses such as SCSI.