Virus

⚠️ Is the most common type of malware,
and it's defined as a malicious program that can execute itself and spreads by infecting other programs or files.

⚠️ A virus is a piece of software that can "infect" other programs by modifying them.

⚠️ Similar to biological virus: Replicates and Spreads Some exists to simply replicate
themselves.

⚠️ Others can do serious damage such as erasing file…

@Computer_science_course

Worm

⚠️Is a type of malware that can self-replicate without a host program.

⚠️ Worms typically spread without any human interaction or directives from the malware authors.

⚠️ A Trojan horse is a malicious program that is designed to appear as a legitimate program.

⚠️ once activated following installation, Trojans can execute their malicious functions.

@Computer_science_course

Spyware

⚠️ Is a kind of malware that is designed to collect information and data on users and observe their activity without users' knowledge.


Other types of malware include functions or features designed for a specific purpose.

Ransomware

⚠️ for example, is designed to infect a user's system and encrypt the data.

⚠️ Cybercriminals then demand a ransom payment from the victim in exchange for decrypting the system's data.

@Computer_science_course

Computer Number System

1. Bit:
📌 Is the smallest unit of data representation.
📌 Is a space that can hold a single state.

2. Byte:
📌 Is the smallest unit of data measurement.
📌 Is a single group of 8 bits. [1 Byte = 8 Bits.]

3. Word:
📌 Is a group of 8 Bytes. [1 word = 8 Bytes.]

@Computer_science_course

Decimal Number System

Z = {0,1,2,3,4,5,6,7,8,9};
Base = 10

📌 Each position to the left of a digit increases by a power of 10.

📌 Each position to the right of a digit decreases by a power of 10.

@Computer_science_course

Binary Number System

📌 Has two states 1(ON state)
and 0(OFF state).

Z = {0,1};
Base = 2

Unsigned number representation

With n bits we can represent 2^n unsigned integer numbers.

⚠️Remember: This ^ Indicates The Power Of

❗️ Range: from 0 to 2^n -1

So with 8 bits we can represent 2^8 = (256) numbers from 0 to 2^8 -1 = (255).

📌 Each position to the left of a digit increases by a power of 2.
📌 Each position to the right of a digit decreases by a power of 2.

Example:
(11001)2 = 1*2^0 + 0*2^1 + 0*2^2 + 1*2^3 + 1*2^4
= (25)10

@Computer_science_course

Octal Number System

Z = {0,1,2,3,4,5,6,7};
Base = 8

📌 Each position to the left of a digit increases by a power of 8.

📌 Each position to the right of a digit decreases by a power of 8.

@Computer_science_course

Hexadecimal Number System

Z = (0,1,2,3,4,5,6,7,8,9, A, B, C, D, E, F};
Base = 16

📌 Each position to the left of a digit increases by a power of 16.

📌 Each position to the right of a digit decreases by a power of 16.

@Computer_science_course

▶️ Computer Number system summary

@Computer_science_course