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/* Illustrations and explanations of digital audio */
* A 8-bit signed sample has values between -128 and 127. In this range, -128 represents a low amplitude, and 127 high amplitude, and the amplitudes increase linearly from -128 to 127.
Both methods can represent the same data, just in different ways (techies will be able to compare this to their knowledge of Z80 assembly), so there is no advantage to using either. The original reason for the two methods is due to the original method to playback the sound. Modern sound cards can play audio stored in both ways.
On a side note, the WAV sound container only allows 8-bit unsigned samples, so there is no ambiguity as to how to interpret 8-bit samples.
Note that both (albeit more obvious in the latter) share a feature typical of binary-encoded numbers: there is no exact 'centre' value, because the total number of possible values is even. In the context of audio, this means that, if the signal spanned the entire range, its centre (average) would be slightly off-zero (in this case, below), which is known as a DC offset. However, even if this did occur, it would be negligible and certainly not audible by humans!
The fact there is no 'centre' value is actually a good thing, as the CPC as to convert the sound signal that comes in to a single bit, determining whether the signal is low or high.
== Duplication of cassettes ==
