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The WHT control system differs substantially from the earlier INT and JKT systems. Whereas the INT and JKT systems have very little 'intelligence' in the instrument controllers, for the WHT system all the instrument controllers are microprocessor based.
The system is arranged as a distributed control system with a VAX 4000 computer providing overall supervisory control over the local control microprocessor systems located in the control room and on the telescope. Low-level instrumentation control uses 6809 (known locally as 4MS), 68008 or 68020 microprocessors. For example, the Detector Memory System, which is a generic detector image acquisition, storage and manipulation subsystem, is based on a 68020 processor in a VME chassis. Communication between the systems is provided across an Ethernet based Utility Network, whilst transfer of image data occurs across dedicated links. In addition, a dedicated hardware link is provided between TAURUS and the IPCS to synchronise data acquisition with scanning of the Fabry-Perot etalon.
The VAX 4000 is also linked via DECnet to the telescope control computer (MicroVAX II), a VAXstation 3100 running the user interface, and a data reduction computer (VAX 3500).