Introduction

The Hartebeesthoek 26m telescope is at present controlled by a suite of computer programs running on an HP 1000 E series computer. This computer was bought more than 13 years ago and is now out of date. The HP 1000s are not manufactured anymore and are becoming increasingly difficult and expensive to maintain. Proof that the HP 1000 has served a good purpose is that it is still running and controlling the telescope today. However it is limited in CPU power, memory, disk space and networking capabilities. It also does not support modern software and hardware standards. New technology is available on the market today which offers much more disk space, cpu and memory and a modern working environment at affordable prices. The new technology is mainly in the form of low-cost PC's. A decision has therefore been taken to replace the HP 1000's with PC's and at the same time rewrite the telescope control system.

This document presents the requirements of the new computer control system (NCCS). It will serve as the basic requirements list for the followup document - the Design Document. Where a solution and/or standard has already been adopted it will be clearly stated so. Consequently this document is more than simply a list of requirements. It also includes a list of specifications and has therefore been called the - Requirements and Specifications Document.

The information presented in this document has been obtained by the authors after discussions with other HartRAO staff and users and browsing through the existing documents. In drawing up the document the authors have tried to be as precise as possible.¹

The authors welcome and need all constructive feedback which results from reading this document. Readers who find inaccuracies or features which are missing and would like to see them incorporated should inform the authors. Not doing so could or will result in features NOT being implemented in the first version and maybe NEVER being implemented because the design of the system excludes them. This is therefore a desparate plea to all readers and future users of the NCCS to provide the authors with feedback.

In writing this document a distinction has been made between requirements and specifications which are mandatory (marked with a $\surd$) and those which are desirable (marked with a $\heartsuit$). The number of $\heartsuit$s indicates the level of desiredness (more $\heartsuit$s means more desirable). In the text the same distinction is made between these two classes of requirements and specifications by employing the words must and should respectively. Deadlines are marked with a $\clubsuit$ and are to be taken very seriously.