Expert Sleepers Silent Way v2.4.3 - Manual (Page 85)

Random
Pressing the ‘Random’ button shows controls for the Step LFO’s random step generator.
This is a software take on the popular shift-register based method of random CV genera-
tion found in a number of hardware synth modules. Google for ‘random shift register cv’
and you should get the idea.
The basic idea is that you have a number of binary ‘bits’ (often 8 or 16 in a hardware im-
plementation) which rotate around a register (essentially a very small element of computer
memory). As each bit leaves the end of the register it may or may not be inverted before it
re-enters the register at the other end. The random element controls whether the bit gets
inverted or not. The beauty of this scheme is that by controlling the randomness of that
change (to make the inversion more or less likely) you can control whether the sequence is
completely random, slowly changing, or completely static.
To turn the register full of bits into a random signal, in the hardware world a DAC (digital
to analogue converter) is used. The bits are simply interpreted as a binary representation
of a number (0 to 255 for an 8 bit DAC), and that is the value of the output signal takes at
that time.
This being a software implementation, it can of course do things that would be hard or ex-
pensive in hardware.
The bits in the shift register are visualised in a display just above the main step editor:
Enable
The ‘Enable’ button turns the random generator on. When it’s running, the shift register is
advanced synchronously with each step of the Step LFO itself. The random value is writ-
ten over the existing step value; conversely, when you disable the random generator, the
random pattern remains in the step editor for possible manual tweaking.