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The system computer

The system computer has three principal roles as part of the data-acquisition system:

• The system computer, running the ADAM system, is responsible for coordinating the entire data-acquisition process.
• The data acquisition system writes the data to files on the system computer data-disk, ready to be archived.
• The system-computer hosts the tape drives and runs the software that allows the data to be archived.

On completion of an exposure, the data is automatically transferred from the DMS to the system computer. The FITS-header information associated with that data will have been collected by the system computer, either during the exposure, or on completion of the exposure. Data and headers are then merged into a data-file on the system computer disk. Finally, two copies of the data are written to tape; a FITS format tape (the D-tape) for the La Palma archive, and either a FITS tape or a VAX-backup tape (the C-tape) for the observer. The observers are responsible for making the D-tapes, but may request the observatory staff to make up the C-tapes (by copying FITS files off the D-tapes). See the separate manual WHT-FITS-2 for details.

The system computer is networked to various VAXes, VAXstations and SPARCstations. If desired, data can be copied across to these machines for immediate reduction and analysis.