1. Concepts of CS
Lecture 1

2. What is a computer?

3. Computer programs and algorithms
A computer is a device that accepts inputs , processes data, and produces output according to a stored program .
A computer program is a set of instructions written by a programmer using a programming language that tells a computer how to solve a problem or carry out a task.
An algorithm is an abstract or a general procedure of instructions for solving a problem using the inputs followed by data processing and ending with the desired output.

5. Architecture of Modern Computer
ALU
ROM
Input CU
Output
RAM
Registers
CPU
Internal Memory
External Storage

6. Central Processing Unit (CPU)
The CPU of most modern computers are microprocessors, which is an electronic component that can be programmed to perform tasks (processing) on data it receives.
CPU is the main unit of the computer which is responsible for executing the instructions stored in the internal memory.
CPU includes:
Arithmetic and logic unit (ALU):
that performs all arithmetic and logical operations.
Control unit (CU):
it is responsible for controlling all the CPU operations including decoding the instructions stored in the main memory.

7. Internal Memory
It is composed of chips of integrated crcuits which are cabable of storing and retreivng data quickly. Thee are two types of internal memory:
Read Only Memory (ROM)
Random Access Memory (RAM)

8. External Storage
The space where data and programs are stored permanently even when the power is turned off.
Nonvolatile external memory
Magnetic tapes, magnetic disks, compact disks (CD), Flash memory, Floppy disk,

9. Computer Inputs

10. Computer Output

11. Computers types
Computers ca be classified according to the size and computational space into:
Super computers
Mainframes computes
Minicomputers
Microcomputers

12. Personal Computers

13. Workstation Computers

14. Videogames are computers

15. Why computers sometimes called serves or clients?
When a computer becomes a client?
Which computer can be used as a server?

16. Super Computers the highest in speed The most expensive type
Costs tens of millions of dollars
Able to tackle complex tasks and
Handle compute- intensive problems:
Weather simulation and forecasting
simulate Nuclear explosions
Complex scientific applications.

17. Mainframe Computers
A large size computer that is able to store huge amount of data.
It supports hundreds to thousands of users simultaneously.
It provides multitasking efficiently.
The cost ranges from hundred thousand to millions of dollars.

18. Minicomputers
They are similar to mainframes but on a smaller scale and less power.
Such computers’ cost ranges from ten thousands up to several hundred thousands of dollars.

19. Microcomputer
They are computers in which the CPU is manufactured as a single chip called “microprocessor”
Compared with previous types, they are the lowest in power and cost.
They include the following different types of computers:
Personal computes
Desktop computer
Mobil or portable computer
Notebook
Tablet
Ultra-mobile
Handheld computers
Workstations
Videogames consoles

20. Numeric data epresentation

21. Text data representation

22. Text Data representation

23. ASCII Codes