Hardware

Hardware - these are physical components of a computer systems. In simplified terms

these are the electronic components, boards, peripherals and computer equipment that
make up a computer system. It is classified into two categories:

i. Internal Hardware – is the interior hardware housed inside the system unit for
example mother board , Central Processing Unit (CPU) etc.
ii. External hardware – hardware outside the system unit also referred to as
peripherals include monitors, keyboards, mice, printers, and scanners.

The system unit –

- The computer system unit is the enclosure for all the other main interior components
of a computer. It is also called the computer case, computer chassis, or computer
tower.
- Is the main box that contains the essential electronic parts such as mother board,
processor, hard drive, Random Access Memory (RAM?

Peripherals – are all the devices that plug into the system unit. These can be input/
output devices.

The Central Processing processor

 is a powerful microprocessor chip in your computer or device that carries out the
instructions from all programs that run on a device.it is able to do millions of
calculation per second and controls the memory access; logic control and central
processing of data in computer and devices.
 The speed of the processor is measured in Megahertz (MHz) which means million
cycles or instructions very second. The processor is made up of the following:
 The control unit- responsible for supervising the operations of the processor. It
does the’ Fetch and execute job’ that is retrieving instructions from memory
and executing them accordingly. Fetch –Decode –Execute Cycle also known
as the instruction cycle is the cycle that the central processing unit (CPU)
follows from boot-up until the computer has shut down in order to process
instructions. It is composed of three main stages: the fetch stage, the decode
stage, and the execute stage.
 The Arithmetic Logic Unit (ALU) - receives data from the CU and performs
either Arithmetic operations (add, multiply, divide, subtract) or logic
operations( making comparison and taking an action based on the result).

An example: If A= 2 END, Else Begin.

Registers – are storage locations inside the processor. CU registers keep current
instructions and the operands of the instructions and ALU registers stores data items
that are to be added, subtracted, multiplied, divided or compared

Functions of Registers:

 Input registers are used to carry the input.

 Output registers are used to carry the output.
 Temporary registers store data temporarily.
 Address registers store the address of the memory.
 The program counter stores the address of the instructions.
 Data registers hold the memory operand.
 Instruction registers hold the instruction codes.

Memory Address Holds the memory location of data that needs to be

MAR
Register accessed

MDR Memory Data Register Holds data that is being transferred to or from memory
 Where intermediate arithmetic and logic results are
AC Accumulator
stored

Contains the address of the next instruction to be

PC Program Counter
executed

Current Instruction
CIR Contains the current instruction during processing
Register

Buses

- Buses are the means by which data is transmitted from one part of a computer to
another, connecting all major internal components to the CPU and memory.
- A bus is a link between the different components of the computer system and the
processor. They are used to send signals and data from the processor to different
devices and vice versa.
- Each wire transmit one bit of data
- A standard CPU system bus is comprised of a control bus, data bus and address bus.

Functions of Bus:

It is used to share data between different devices.


It supplies power to different components of the system.

Memory Unit

- The memory unit consists of RAM, sometimes referred to as primary or main

memory. Unlike a hard drive (secondary memory), this memory is fast and also
directly accessible by the CPU.
- RAM is split into partitions. Each partition consists of an address and its contents
(both in binary form).
- The address will uniquely identify every location in the memory.
- Loading data from permanent memory (hard drive), into the faster and directly
accessible temporary memory (RAM), allows the CPU to operate much quicker.
- The MAR and MDR registers are used to carry out READ and WRITE operations to
and from the memory
Factors that affects the performance of the CPU

i. Clock

- As the name suggests, the clock controls the timing and speed of the functions of
different components of the CPU.

- It sends out electrical signals which regulate the timing and speed of the functions.

Functions of Clock:

 It maintains the synchronization of the components of the computer system.

 It keeps track of the current date and time.
ii. So, this is all about the major components of the CPU which are responsible for the
smooth processing of instructions and data in the computer system.

iii. Cache

- Cache is a type of memory located in the CPU it self, stores small amounts of data
and instructions temporarily which can be reused as and when required.

- It reduces the amount of time needed to fetch the instructions as instead of fetching it
from the RAM, it can be directly accessed from Cache in a small amount of time.

- It has much father data access than RAM, it stores frequently used instructions and
data that need to be accessed faster thereby improving the performance of the CPU

- Nb** when the CPU need to read the memory, it first check the cache and move on to
the main memory which is the RAM if the data is not in the cache

- The large the cache memory the better the CPU performance.

Functions of Cache:

 They reduce the amount of time needed to fetch and execute instructions.
 They store data temporarily for later use.

iv. Core

- The use of different core may improve computer performance

- One core is made up of an ALU, CU and registers thus dual core is made of two cores
and quad is made up of four core etc
- The way the CPU communicates with each core determines it performance hence it’s
not about the number of cores. In a dual core the CPU communicates with its cores in
a single channel hence reducing the performance

QTS

Compare the performance of a dual core computer and that of a corei5.