overview of computers

Question 1

computers

Answer 1

Machines which receive, store, process, and output information can deal with data of all kinds :numbers, text, images, graphics, and sound.

Question 2

hardware

Answer 2

is the equipment used to perform the necessary computations which includes: the central processing unit (CPU),Memory, monitor, keyboard, mouse, printer, and speakers.

Question 3

software

Answer 3

consists of the programs that enable us to solve problems with a computer by providing it with lists of instructions to perform.

Question 4

hardware: components of a computer

Answer 4

cpu: central processing unit 
main memory 
secondary storage 
input devices 
output devices

Question 5

how is communication done in the memory

Answer 5

done using three busses
1-Data Bus (To read/write the actual data).
2- Address Bus (to identify the exact memory cell to read or write).
3-Control Bus (to control if I want to read or write).

Question 6

content of the cell

Answer 6

the data stored in a memory cell

Question 7

memory definition

Answer 7

1000 memory Cells.
A memory cell is a grouping of smaller units called bytes
A byte is composed of even smaller units of storage called bits.
The term bit , derived from the words binary digit, is the smallest element a computer can deal with.

Question 8

numbering system

Answer 8

A numbering system is a systematic method for representing numbers using a particular set of symbols.

Question 9

binary system

Answer 9

Binary refers to a number system based on two numbers, 0 and 1, so a bit is either a 0 or a 1
Generally, there are 8 bits to a byte.

Question 10

main memory

Answer 10

Stores programs, data, and results.

Question 11

types of main memory

Answer 11

Random access memory (RAM): Temporary storage of programs and data.
Usually volatile memory : which means that everything in RAM will be lost when the computer is switched off.

Read-only memory (ROM):
Stores programs or data permanently. Not volatile: the data stored there do not disappear when the computer is switched off.

Question 12

cpu

Answer 12

central processing unit
ROLES: has 2 roles (coordinating all computer operations. performing arithmetic and logical operations on data.)
USAGE: (Follows the instructions contained in a computer program to determine which operations should be carried out and in what order.)

Question 13

fetching

Answer 13

a technique used by the cpu to retrieve each instruction in sequence

Question 14

registers

Answer 14

Register memory is the smallest and fastest memory in a computer. It is not a part of the main memory and is located in the CPU in the form of registers
CPU’s current instruction and data values are stored temporarily inside the CPU in special high-speed memory locations

Question 15

machine cycle

Answer 15

1: fetch instructions from memory from main memory by the cpu
2: decode instructions into commands in the cpu
3: excute all commands in the ALU (arithmetic logic unit)
4: store results in memory

Question 16

operating system

Answer 16

It is the software that is responsible for directing all computer operations and managing all computer resources.
eg: ubuntu

Question 17

ALU

Answer 17

arithmetic logic unit (ALU), a memory unit, and input/output (I/O) controllers. The ALU performs simple addition, subtraction, multiplication, division, and logic operations, such as OR and AND.

Question 18

memory cell

Answer 18

The memory cell is the fundamental building block of computer memory. The memory cell is an electronic circuit that stores one bit of binary information and it must be set to store a logic 1 and reset to store a logic 0. Its value is maintained/stored until it is changed by the set/reset process

Question 19

computer languages

Answer 19

Developing new software requires writing lists of instructions for a computer to execute.
** The Computer only understand machine language ( Machine language is a collection of binary numbers.)
** Software developers rarely write in the machine language // Another drawback of machine language is that it is not standardized.
There is a different machine language for every type of CPU.
Assembly language is more readable.

Question 20

assembly

Answer 20

A language in which computer operations are represented by mnemonic codes rather than binary numbers.
Variables can be given names rather than binary memory addresses.
Each assembly language instruction corresponds to exactly one machine instruction.

Question 21

high level langues

Answer 21

used: To write programs that are independent of the CPU.
** Combine algebraic expressions and symbols taken from English.
It is easier to express problem solutions in high-level languages.

Question 22

compiler

Answer 22

because computers do not understand high level languages, we compile the high level language before executing the program to translate the languages into the target computer machine languages
the program that does this process is called a compiler

Question 23

pwd

Answer 23

(print working directory)

command displays the full pathname of the current working directory.

Question 24

ls

Answer 24

(list)

command lists all files and folders in your current working directory.

Question 25

mkdir

Answer 25

(make directory)
command allows you to create a new directory. You can specify where you want the directory created –if you do not do so, it will be created in your current working directory.

Question 26

cd

Answer 26

(change director)

command used to change the current working directory.

Question 27

gedit

Answer 27

Text Editor (gedit)
To create or open (if exists) a specific file

Question 28

gedit

Answer 28

Text Editor (gedit)
To create or open (if exists) a specific file

Question 29

cat

Answer 29

It is used to display the content of a file in the Terminal, starting from the first row and finishing on its last row.

Question 30

cp

Answer 30

(copy)
command allows you to copy a file. You should specify both files: the file that you want to be copied and the location that you want it copied to.

Question 31

rm

Answer 31

(remove)

command removes the specified file.

Question 32

main function

Answer 32

Every C program has a main function. The parentheses following the word “main” indicate that it is a function. after main function execution begins

Question 33

printf()

Answer 33

used to print anything is written between quotation marks “ ” onto the screen.
This function is defined in the standard input/output file “stdio.h”, which is a header file in C language.

Question 34

semicolon in c

Answer 34

end of statement

Question 35

include

Answer 35

Tells the compiler where to find the meaning of printf() function.
It is called preprocessor directive.

Question 36

return statement

Answer 36

The return statement transfers control from a function back to the activator of the function.
For function main , control is transferred back to the operating system.

Question 37

reserved words

Answer 37

Appear in lowercase, Have special meaning, Cannot be used for other purposes

Question 38

standard identifiers

Answer 38

Have special meaning, Can be redefined and used by programmer (not recommended),Examples : printf, scanf

Question 39

User-Defined Identifiers

Answer 39

Constants

Variables

Question 40

Syntax Rules:

Answer 40

1) An identifier must consist only of letters, digits, and underscores
2) An identifier cannot begin with a digit
3) A C reserved word cannot be used as an identifier
4) An identifier defined in a C standard library should not be redefined

Question 41

Program outline

Answer 41

Preprocessor Dircetives
int main()
{
Function body
}

Question 42

Code Compilation

Answer 42

gccsourceFile.c–o outputFile

gcc: is the name of the compiler.
sourceFile.c: is the name of your c file.
-o: the name after it will be the executable output file name.
outputFile: you can choose your output file name.