Control Memory

The control unit of a computer controls all the operations within it. The function of control unit is to generate relevant timing and control signals for the execution of
instruction (operation) in the computer. It controls the flow of data between the processor (Arithmetic and logic unit) , memory and other peripheral device (any input or output device). for example, the main memory receives two kinds of control signals from the control unit. One is memory read (MRD) which is generated by the control unit when the data is to be read from the Memory and another is Memory Write (MWR) which is generated by the control unit when data is to be written to memory. Similarly, all the registers receive control signals from control unit. For example, AC (Accumulator) receives the control signal like Increment accumulator or Clear accumulator, Shift left, Shift Right etc.

There are two approaches of control unit design and implementation.

1. Hardwired Control

2. Micro-programmed Control