Control Unit

-The ControL Unit can be thought of as the brain of the CPU itself.
-It controls based on the instructions it decodes, how other parts of the CPU and in turn, rest of the computer systems should work in order that the instruction gets executed in a correct manner.

-There are two types of control units, the first type is called hardwired control unit.
-Hardwired control units are constructed using digital circuits and once formed cannont be changed.



-The other type of control unit is microprogrammed control unit.
-A microprogrammed control unit itself decodes and execute instructions by means of executing microprograms.

The Arithmetic Logic Unit

-The Arithmetic Logic Unit (ALU) is essentially the heart of a CPU.
-This is what allows the computer to add, subtract, and to perform basic logical operations such as AND/OR. Since every computer needs to be able to do these simple functions, they are always included in a CPU.

SYMBOL OF ALU

Functions of Arithmetic Logic Unit:

• Almost all the actions of the computer are done by it. It gets its data from a certain computer memory called processor register . After the data gets processed, its results get stored in output registers of the arithmetic logic unit .

• The arithmetic logic unit can perform integer arithmetic operations like addition, subtraction, etc.

• It can also perform bitwise logic operations like AND, OR, XOR, etc.

• The arithmetic logic unit performs bit-shifting operations like rotating or shifting a certain word to either the left or the right by a given number of bits. These can also be represented as divisions by 2 and also multiplications by 2. These are the simple operations carried out by the arithmetic logic unit .

Components Of System Unit

A system unit is a case that contains electronic components of the computer used to process data.

The most common components are inside a system unit are:
1.The processor
2.The memory
3.Adapter cards e.g. sound card, modern card, video card, network card.
4.Ports
5.Drive bays

6.Power supply

Motherboard: The main circuit board in system unit is called the motherboard, it contains adaptor cards processor and memory chips.

Chip: A chip is a small semi-conducting material where intergrated circuits can be etched. Integrated circuits have many microscopic pathways capable of carrying electric current.

Central processing unit (CPU): The CPU carries and interprets basic instructions that can operate a computer. The control unit coordinates operations in a computer. The Arithmetic logic unit (ALU) does arithmetic, comparison and logical operations. This can also be known as the processor.