Control Unit and Register Array. As the name indicates ALU performs all arithmetic and logical operations on the data received from input devices or memory. Register array consists of a series of registers like accumulator (A), B, C, D etc. which acts as temporary fast...
For this circuit, the "clock out" signal of the CD4017 is applied to the base of the transistor (through a resistor and diode) which in turn allows current to flow from the collector to the emitter. This should turn the four corner LEDs on for five clock cycles, and off for five. So...