The data acquisition and control systems for the William Herschel Telescope use a "mimic" display to
present an easily assimilated view of the status of the telescope, its instruments and detectors. This
display is specified in a set of data files that can easily be modified to reflect any changes to the system.
A mimic description language, developed at the RGO, is used to describe individual "pages" of the
complete mimic display. Such pages can represent various levels of complexity, from complete subsystems
down to individual mechanisms. Extensive use is made of colour graphics to allow the user to see the
state of any item on the display at a glance. The mimic system also uses colour to warn the user of
errors occurring in pages which are not currently displayed, and by this means can indicate or even force
the display of those pages to which the user should refer as a matter of priority.
The mimic display is directly driven by the low-level processes responsible for controlling the instruments
and detectors. The location of the information to be displayed is retrieved from globally accessible
memory and displayed according to the prescription for that group of items in the mimic description