The ASCCHAT program supports the full tele-command and telemetry structure of the ASC. It might be used for a variety of purposes such as: Familiarisation with the command structure of the ASC. Support for checkout of the ASC functionality. Support for real sky verification and performance envelope of the instrument. Support for closed loop testing. Generation of upload commands. Upload of software updates. Upload of new parameter values. Debug dump device during system integration. Off-line operation of the instrument. Support for internal calibration measurements. Support for inter-calibration measurements. SCOE.