[hetman]

Digital doesn't mean binary. A digital system must simply occupy a fixed number of levels, rather than the contiguous values of an analogue system. Binary systems, with 1 and 0, just happen to be one example of that.

There's plenty of non-binary schemes used in modern digital systems though. Modern NAND flash is one instance, for example QLC SSD drives store 16 distinct levels per storage cell (allowing each to encode the equivalent of 4-bits of data). Another example is 64-QAM, a modulation scheme used in a variety of places, including 802.11n Wi-Fi and Digital Terrestrial television (among others), which forms symbols out of two out of phase sinusoids, each of which can take up to 8 amplitude levels.

And even electronic computers haven't always been binary, one of the early Soviet computers was ternary, relying on 3 digits rather than the more familiar 2, to do all of its core computing functions.