Robert J Morton

Personal Project ROBOS: a multi-tasking multi-processing message-driven real-time operating system and building frame for specialised PC-based applications.

Robos is a development code name. It stands for Rob's Operating System. Robos runs as an application on a normal host operating system such as PC DOS. It is a very compact operating system which is closely linked with the applications it runs.

All Robos applications - and a good proportion of Robos itself - are made up of software objects of a kind known as message-driven finite-state machines [MFMs]. Each MFM runs as an independent task. Robos currently makes provision for running up to 255 such tasks at once.

The kernel of Robos is a message exchange which provides an orderly channel through which MFMs pass messages between each other. Some MFMs perform general services, some perform applications-related services. Others perform the input/output services needed to allow applications to accept messages from, and send messages to, the external world.

An MFM comprises a set of data instances and a set of message processing functions [MPFs]. On receiving a valid message from the central Message Exchange, an MPF updates the appropriate data instance and then puts an appropriate output message on the Message Exchange's message queue.

Each data instance is designed as a logical machine which can at any given time be in any one of a small finite number of complex logical states. While in a given state, such a machine may receive a message of any one of a prescribed number of valid types. Such a message may simply supply data, trigger a change-of-state, or both.

Robos, and each of its applications is developed as a formal set of source files. The Robos message exchange, input/output services and internal MFMs are kept as an object library. Each application MFM is then developed as a separate file-set. It is then compiled and linked with Robos as an overlay object or compiled as a .dll file to be linked dynamically at run-time.

NOTE: Robos was conceived during the mid-eighties and written in the early nineties. Today's object-oriented programmers may recognise the Robos 'MFM' as a special case of what has become known nowadays as a class, and its data instances as objects of that class. Similarly, MPFs may be recognised as what now would be know as the class's constructors and methods.