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mechanical and hydraulic

May 1, 1800

This period began during the Industrial Revoution of the 1800's. The development of control systems at this stage was based on mechanical devices, with inventors having little understanding of how the devices could be automatically controlled. Developments in control systems during this period were slow and not usually planned. This meant that future developments were not really catered for.

Direct Digtial

May 1, 1959

in 1959, the first digtial computer was used to control an automated system. Computers were often used to monitor the control system from a central location and still used analogue controllers. The development of control systems during this stage was still limited by the slow and unreliable computers available at that time. During the direct digital period it became recognised that there was a growing need for: more organised methods of controlling systems, which could be achieved by viewin

Minicomputer

May 1, 1965

in 1965, the first minicomputer was introduced by Digital Computer Corporation (DEC). During this period, improvements in computing technology had a direct impact on process control. Computers became extremely reliable and able to process large amounts of data more quickly. The number of computers used in automated control grew extensively.

Microcomputer

May 1, 1972

In 1972, the microcomputer appeared nd made significant changes to the way computers were used. Programmable controllers were developed and replaced by older styles, which used hardwire relay logic. This meant that process controllers could be built for control systems.