PC-based test instruments are nothing new. By using the processing power and graphical interfacing capabilities of the PC, manufacturers have been able to dramatically improve the price/performance ratio of their test equipment.

The advantages of combining test equipment with the power of the PC are not lost on Australian company BitScope Design, who manufacture a small range of mixed-signal oscilloscopes and accessories. BitScope first appeared in 1998, when Australian design engineer Norman Jackson described his "Mixed Signal Capture Engine" in the pages of Circuit Cellar. He won first prize in a competition for his efforts.

Subsequently, BitScope went on to offer several designs as do-it-yourself kits. These proved to be very popular but have been recently discontinued, as several through-hole components used in the kits are no longer available. The current models all use surface-mount technology and are therefore sold preassembled and tested.

Despite the shift to preassembled units, the same core principles apply to all BitScope instruments. Their "open design" policy means that all units are supplied with circuit diagrams so that you can see how they work. In addition, detailed architectural information is provided on the BitScope website for those that wish to write their own virtual instrumentation applications.