On the "backend" are various circuits which sit "behind" one or more frontend registers. These are the ZOZ objects which have been placed onto the WIZ. They vary from WIZ to WIZ, and can be any kind of silicon-based circuits.

For example, we could have a multiplier circuit, sitting behind registers 2, 3, and 4. It could constantly monitor registers 2 and 3 and always keep register 4 equal to their product. To use it, we would write an instruction sequence like this:

   X => 2 ; Y => 3 ; 4 => Z    // Compute: Z = X + Y

In other words, we copy register X and register Y to registers 2 and 3, and then read register 4 to get our answer, which we copy to register Z.