AMSTRAD cpc 6128 User Instruction page 381

If this process sounds cumbersome, then you're quite right, as you have uncovered the
first and most important truth about computing. A computer is primarily a tool for
performing the simplest of repetitive tasks very quickly and with absolute precision.
Thus BASIC interprets the instructions as given in the form of the program, and
translates them into the language that can be handled by the CPU. Only two states
are understood by the logic of a computer - 'yes' or 'no', represented in binary notation
as '1' and '0'. The representation in Boolean logic is simply 'true' and 'false' -there's no
such thing as a 'maybe' or 'perhaps'!
The process of switching between these two distinct states is the essence of the term
'digital', and is sometimes referred to as 'toggling'. In the world of nature, most
processes move gradually from one completely 'stable' state to another in a linear
progression. In other words, the transition is made by following the path of a line
between the two states - in an ideal digital environment the switch from one state to
the next is made in no time at all-but the physics of semiconductor science dictate
that there will be some minor delay, referred to as propagation delay - and it is the
accumulation of many of these propagation delays that provides the reason why a
computer has to spend some time processing the information before the answer comes
out.
Chapter 9 Page 8
At your leisure ....