Introduction

  The INT is controlled by a Perkin-Elmer 3220 computer interfaced through CAMAC. The computer system is found in the CLIP Centre, a temperature-controled clean room on the second floor of the INT building, west of the central void. The machine stands in the south-west corner. Both computer and its AMPEX disk drive are powered via the Buffer Set.

Control of the computer is via one of two terminals: either from the System Console in the Telescope Control Room, on the third floor, standing on the far left-hand side of the Control Desk, or from the Local Console in the CLIP Centre, a standard VT220 terminal on the desk next to the PE 3220. The two-position switch for selecting either Control Room or CLIP Centre normally stands right beside the Local Console.

The PE 3220 software is controlled by the Telescope Operator via the User Interface, which is the VDU currently standing on a small table to the left of the Control Desk in the Telescope Control Room. The computer drives the ``Information Display'', which is a monitor showing the Date, Time and Positions of the current or next sky object. The Operator can move this Information Display to any of a selection of different monitors by pressing the appropriate button(s) on the Control Desk. Such is also the case for the MIMIC display (both Cassegrain and Prime Focus), and for the Autoguider Display. The PE 3220 also takes care of some of the Control Desk hardware, in particular the Beckmann Displays, which display the UTC, LST, RA, Dec and Zenith Distance in red illuminated numerals.