GPIB

General Purpose Interface Bus (GPIB) or Hewlett-Packard Interface Bus (HP-IB) is a short-range digital communications 8-bit parallel multi-master interface bus specification originally developed by Hewlett-Packard and standardized in IEEE 488.1-2003. It subsequently became the subject of several standards. Although the bus was originally created to connect together automated test equipment, it also had some success as a peripheral bus for early microcomputers, notably the Commodore PET. Newer standards have largely replaced IEEE 488 for computer use, but it is still used by test equipment. In the 1960s, Hewlett-Packard (HP) manufactured various automated test and measurement instruments, such as digital multimeters and logic analyzers. They developed the HP Interface Bus (HP-IB) to enable easier interconnection between instruments and controllers (computers and other instruments). This part of HP was later (c. 1999) spun off as Agilent Technologies, and in 2014 Agilent's test and measurement division was spun off as Keysight Technologies. The bus was relatively easy to implement using the technology at the time, using a simple parallel bus and several individual control lines. For example, the HP 59501 Power Supply Programmer and HP 59306A Relay Actuator were both relatively simple HP-IB peripherals implemented in TTL, without the need for a microprocessor. HP licensed the HP-IB patents for a nominal fee to other manufacturers.