...This conversion from Analogue to digital is performed by an aptly named Analogue to Digital Converter chip, ADC for short. The BBC has a build in ADC for analogue joysticks but this is too slow for the frequencies in sound. The computer using the sampler must be driven by suitable software which takes a sample and saves it to disk. Once the sample is saved to disk, your own prog can load it and use a little machine code routine to play back the sample. The BBC's sound system however leaves a lot to be desired when playing back samples and playback quality can be disappointing.