Introduction to embedded systems

Embedded systems is the name given to equipment which contains some form of timing or date function.

The timing or date function is based on an electronic clock buried within the system.

This clock is used by a microprocessor to control the equipment.

Associated with the microprocessor is also a read only memory, which contains some programming code.

In some equipment, the clock, the microprocessor, and the read only memory will be seperate components. In other equipment, one component will contain all three items.

It does not make any difference, however, as the problem with these systems is that the programming code does not exist in neat layers that are commonly used and understood, but exists as a unique entity, understood by only a few people such as the programmer.

Also, some equipment does not have an interface where users can deliberately fast forward the date, to see if the equipment is compliant.

Additionally, even if the equipment can be proved to be non-compliant, it is unlikely that it is either possible or economically viable to extract the programming code used, work out how it works, modify it to achieve compliance, create new components, install them, and then set the equipment up again.

It would be difficult to test, which is an essential part of software development, as modifying the code could well have introduced bugs which prevent the correct operation of the system.

It is also quite possible that the raw chips required to hold the new programme code are not now available.

There is of course a number of types of equipment which have been made in large volumes as standard items - in these cases it is possible, but by no means certain, that the original manufacturer will create updated components that can be fitted into the equipment.

Unfortunately, in many cases it would cost more to modify the equipment than to replace it.

So there is quite a problem with embedded systems, and part of the problem is that the problem cannot always be quantified or predicted.

© 1999 Ron Turner

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