A computer is a programmable machine that can execute a list of instructions. It has both hardware and software components. The hardware includes the central processing unit (CPU), memory, and input/output devices. The software provides instructions to tell the hardware what tasks to perform and includes both system and application programs. Data is stored in the computer in a format that can be manipulated by the hardware and software.

1. Block diagram of computer

2. A Computer is
• A programmable machine. It can execute or run a pre-
recorded list of instructions which follow certain rules (a
program).
• Modern computers are electronic and digital. The actual
machinery -- wires, transistors , and circuits -- is called
hardware; the instructions and data are called software.

3. Block diagram of computer

4. Components of a Computer System
• Computer hardware provides the physical mechanisms to
process, store, and input /output data. Includes CPU,
memory, I/O devices
• Software provides instructions to tell the hardware what
tasks to perform. It includes system (eg Windows XP) and
application (eg Excel) software
Data in the computer may be representing numbers,
characters, graphics etc but is always kept in a form that
the hardware and software can manipulate.

5. Hardware – I/O
• Input Devices collect & translate raw data into form useable
by computer. e.g keyboard accepts letters and numbers and
converts them to a binary code such as Unicode.
• Output devices produce results in useable form for user (or
another device). e.g. monitor converts binary codes to
characters and images, whilst modem converts digital data
to analog form for transmission over telephone lines.

6. Hardware – I/O Peripherals
1 Input Devices
• Mouse
• Keyboard
2 Output Devices
• Monitor (VDU)
• Printer
3 Secondary Storage Devices
• Hard Disk
• CD / DVD / Floppy

7. Hardware - memory
• Memory - Purpose of memory is data storage. Two major
types of memory :
• Primary memory - to hold data and instructions during
processing
– eg RAM. Relatively limited capacity and volatile
• Secondary memory - to provide permanent long term
storage
– eg hard disk. High capacity and non-volatile

8. Hardware - memory
• Secondary storage consists of non-volatile high-capacity
devices to store programs and data not currently required by
CPU.
• Hard and floppy disks, and tapes store data as magnetized
spots.
• CD’s and DVD’s store data as pits or surface marks
detectable by laser light.

9. Hardware- memory
• Digital computers deal with data in binary form - all data is
represented using just two digits - 1 or 0. Letters and other
symbols are assigned unique binary codes.
• Primary memory consists of a set of locations defined by
sequentially numbered addresses. Each location contains a
binary number that can be interpreted as data or an
instruction.

10. Main Memory (RAM)
1. Different from disk storage
2. used to temporarily store Data
3. in modern computers memory is 512 MB.

11. Central Processing Unit ( CPU)
1. Acting as the brain of the computer’
2. Currently the Intel-Pentium microprocessor is the
most common CPU though there are many types

12. Hardware- the CPU
• CPU performs actual processing of data, according to
instructions from programs.
• Data and programs are stored in primary and secondary
memory, and moved to and from CPU as required.
• Signals representing data and instructions travel between
system components along electronic pathways, called buses.
Capacity of bus is critical to system performance.

13. Hardware - The Processor
• The CPU is a general purpose processor that performs data
manipulation and/or transformation functions including
computations, comparisons and data movement.
• The CPU consists of 3 main parts:
– ALU - where arithmetic and logical operations performed
– Control Unit - controls data movement and execution of
instructions
– Registers - small high speed storage areas

14. THANK YOU