Computer Fundamentals, Architecture, Networking, and Data Representation

Comprehensive review flashcards covering computer hardware, software, operating systems, malware types, network topologies, data representation, binary/octal/hexadecimal conversions, keyboard key categories, and malware countermeasures.

How is a computer defined in the notes?

An electronic device that accepts input, processes data, stores data, and provides output.

What is the primary function of an input device, and what examples are provided?

It helps a user key in or enter data into a computer. Examples include mouse and keyboard.

What are the two parts of a CPU identified in the notes?

The Arithmetic Logic Unit (ALU) and the Control Unit (C.U.).

What is the function of the Arithmetic Logic Unit (ALU)?

It enables the computer to perform all arithmetic functions.

What is the role of the Control Unit (C.U.) in a CPU?

It directs the processor on how and when to process data.

What is the function of storage devices, and what examples are listed?

They store data. Examples include SSD (Solid State Disk), HDD, memory cards, and flash disk.

What is the purpose of output devices, and what examples are given?

To relay feedback to the user. Examples include monitors, projector, printer, and speakers.

What requirement is specified for a computer system to work?

Hardware and software should work together.

How is hardware defined in the notes?

Physical components of a computer that you can touch or feel.

How is software defined in the notes?

Programmes that can be installed in a computer environment.

What is application software, and what examples are noted?

Software that enables a user to accomplish a specific task. Examples include IG, WA, TT, AI demo model, Miro, Duolingo, and ChatGPT.

How is an Operating System (O.S.) defined?

The master program that manages all the operations within a computer.

What is the general purpose of utility software (U.S.) according to Source 1?

To maintain, protect, and improve the performance of a computer.

Who is the developer of Windows OS, and what are its advantage and disadvantage?

Developer: Microsoft. Advantage: User friendly. Disadvantage: Not free / requires a license (can be cracked).

Who is listed as the developer of Linux, what distributions are named, and what are its advantages and disadvantages?

Developer: Linus. Distributions: Kali Linux, Ubuntu, Fedora. Advantages: Open source / free, malware resistant. Disadvantages: Not user friendly / technical and complex.

What are five primary functions of an Operating System listed in Source 1?

1. Manages computer; 2. Detects software errors, hardware faults or failure; 3. Protects system resources and user data from unauthorised access, malware, and threats; 4. Ensures smooth communication between the computer and external hardware; 5. Organizes data into files and directories on storage devices.

What is the day-to-day role of utility software as defined in Source 2, and what are two examples?

Deals with the day to day maintenance of a computer. Examples include Windows Defender and Disk Defragmenter.

What is the function of device drivers?

Enable hardware to communicate with the software.

How is a hacker defined in the notes?

Someone who gains access to electronic info in an unauthorised manner.

What characterizes a Black hat hacker?

Hacks with evil motives.

What characterizes a White hat hacker?

Hacks with pure motives of helping.

What characterizes a Grey hat hacker?

Shares both characteristics of white and black hat hackers.

What characterizes a Blue hat hacker?

Hacks for revenge.

How is malware defined?

Malicious software or "badware" (bad software).

What is spyware?

Malware that spies on electronic devices and steals confidential info.

What is a Trojan horse?

A malware that masquerades or pretends to be an innocent software whereas it has evil motives.

What is ransomware?

A malware used by hackers to encrypt all your files and asks for a payment in order for the files to be decrypted.

What is a zombie computer?

A computer that has been infected by malware.

What is a computer virus?

A malware that can copy itself and spread from one computer or file to another.

What is a file virus?

A malware that attaches itself to application software such that when you run the application, the malware runs in the background.

What is a companion virus?

A malware that creates a file with a similar name to an existing file but with a different file extension (such as $.com$), deletes the original file, and leaves the fake file behind.

What is a boot sector virus?

A malware that automatically starts immediately when you switch on your computer.

What is a computer worm?

A standalone malware that transmits via network security holes and does not require human interaction to spread.

What is a time bomb malware?

A malware that stays in your computer undetected until a specified time.

What is a logic bomb malware?

A malware that stays in your computer undetected until a specified set of commands are met.

What are five symptoms of a computer infected by malware (zombie computer)?

1. Annoying sounds; 2. Restarting without notice; 3. Duplication of files; 4. Depletion of storage space; 5. Computer becomes slow.

How is a computer network defined?

The interconnection of $2$ or more computers in a way that they can communicate and share resources.

What is a Local Area Network (LAN)?

A network that covers a limited geographical area.

What is a Wide Area Network (WAN), and what is the largest WAN in existence?

A network that covers a large geographical area; the largest WAN in existence is the internet.

What is a Metropolitan Area Network (MAN)?

A network that covers a larger geographical area than a LAN but a smaller area than a WAN.

What is a Personal Area Network (PAN)?

A network that connects small personal devices.

What is Network Topology?

The arrangement of computers and networking devices along a network.

Which network topology is depicted in this diagram?

Bus Topology, where computers are connected along a single main cable.

What are the advantages of a Bus topology?

Easiest and cheapest to implement, well suited for temporary networks, typically the cheapest, and failure of one station does not affect others.

What are the disadvantages of a Bus topology?

Performance degrades with traffic, difficult to administer/troubleshoot, limited cable length, a cable break can disable the entire network, and maintenance costs are higher in the long run.

What are the advantages of a Star topology?

Easy to implement and extend, well suited for temporary networks, and the failure of a non-central node will not affect the functionality of the rest of the network.

What are the disadvantages of a Star topology?

Limited cable length, maintenance costs are higher in the long run, failure of the central node disables the entire network, and it is the most expensive topology.

How is a Ring topology structured?

Connected in an enclosed loop where data travels in one direction.

What are four advantages of a Ring topology?

1. Growth of the system has minimal impact on performance; 2. All stations have equal access; 3. Each node acts as a repeater allowing the network to span greater distances; 4. High speeds of transmission because data travels in one direction.

What is a major disadvantage of a Ring topology?

Failure of one computer or cable break may impact or disable other computers on the network.

What are the four number systems or forms of data representation listed in the notes?

Binary, Octal, Decimal, and Hexadecimal.

What is the Binary system, and why is it called Base $2$?

It is the language understood by a computer made up of digits $0$ and $1$. It is known as Base $2$ because it allows only two numbers ($0$ and $1$).

What method is used to convert a negative decimal number to binary?

Two's complement method.

What are the two methods of converting decimal numbers to binary noted in Source 7?

Division method and Position Square method.

Using the division method, what is decimal $9$ converted to binary?

$1001_2$ ($9/2 = 4\text{ rem }1$, $4/2 = 2\text{ rem }0$, $2/2 = 1\text{ rem }0$, $1/2 = 0\text{ rem }1$).

Using the division method, what is decimal $23$ converted to binary?

$10111_2$ ($23/2 = 11\text{ rem }1$, $11/2 = 5\text{ rem }1$, $5/2 = 2\text{ rem }1$, $2/2 = 1\text{ rem }0$, $1/2 = 0\text{ rem }1$).

Using the division method, what is decimal $25$ converted to binary?

$11001_2$ ($25/2 = 12\text{ rem }1$, $12/2 = 6\text{ rem }0$, $6/2 = 3\text{ rem }0$, $3/2 = 1\text{ rem }1$, $1/2 = 0\text{ rem }1$).

How does the position square method convert decimal $14$ to binary?

$1110_2$ (by subtracting powers of $2$: $14 - 8 = 6$, $6 - 4 = 2$, $2 - 2 = 0$).

How is the Decimal number system characterized in Source 8?

Also known as Base $10$, it accepts $10$ numbers ($0\text{--}9$).

What is the decimal equivalent of binary $1010_2$ using positional notation?

$(1 \times 2^3) + (0 \times 2^2) + (1 \times 2^1) + (0 \times 2^0) = 8 + 0 + 2 + 0 = 10_{10}$.

What is the decimal equivalent of binary $10111_2$?

$(1 \times 2^4) + (0 \times 2^3) + (1 \times 2^2) + (1 \times 2^1) + (1 \times 2^0) = 16 + 0 + 4 + 2 + 1 = 23_{10}$.

What is the decimal equivalent of binary $1100_2$?

$(1 \times 2^3) + (1 \times 2^2) + (0 \times 2^1) + (0 \times 2^0) = 8 + 4 + 0 + 0 = 12_{10}$.

What is the decimal equivalent of binary $101011_2$?

$(1 \times 2^5) + (0 \times 2^4) + (1 \times 2^3) + (0 \times 2^2) + (1 \times 2^1) + (1 \times 2^0) = 32 + 0 + 8 + 0 + 2 + 1 = 43_{10}$.

How is the fixed point binary number $101.110_2$ converted to decimal in Source 9?

Whole number: $101_2 = (1 \times 2^2) + (0 \times 2^1) + (1 \times 2^0) = 4 + 0 + 1 = 5$. Fractional part: $0.110_2 = (1 \times 2^{-1}) + (1 \times 2^{-2}) = 0.5 + 0.25 = 0.75$. Total: $5 + 0.75 = 5.75_{10}$.

What is the result when converting fixed point binary $1100.101_2$ to decimal?

$13.75_{10}$ (calculated as whole number $1100_2 = 12$ plus fractional calculations totaling $13.75_{10}$).

How do powers of $2$ change before and after the binary point in fixed-point numbers?

Powers increase to the left of the point ($2^0, 2^1, 2^2\text{...}$) and decrease with negative powers to the right of the point ($2^{-1}, 2^{-2}, 2^{-3}\text{...}$).

How is "Overflow" defined in the notes?

When a number exceeds the maximum value that can be represented.

How is the decimal fraction $0.875_{10}$ converted to binary in Source 10?

$0.875 \times 2 = 1.75$ (carry $1$); $0.75 \times 2 = 1.5$ (carry $1$); $0.5 \times 2 = 1.0$ (carry $1$), yielding $0.111_2$.

What rule is stated for recurring infinite numbers when converting decimal fractions to binary?

For recurring infinite numbers, count $8$ steps.

What is the smallest unit of computer storage?

A Bit (Binary Digit).

How many bits make up $1\text{ Byte}$?

$8\text{ bits} = 1\text{ Byte}$.

How many bytes are in $1\text{ Kilobyte}$?

$1024\text{ Bytes} = 1\text{ Kilobyte}$.

How many kilobytes make up $1\text{ Megabyte}$?

$1024\text{ Kilobytes} = 1\text{ Megabyte}$.

How many megabytes are in $1\text{ Gigabyte}$?

$1024\text{ Megabytes} = 1\text{ Gigabyte}$.

How many gigabytes make up $1\text{ Terabyte}$?

$1024\text{ Gigabytes} = 1\text{ Terabyte}$.

What base is the Octal number system, and how is each octal digit grouped in binary?

Base $8$; each octal digit corresponds to a group of $3\text{ binary bits}$.

Convert the binary string $111000111_2$ to hexadecimal as demonstrated in Source 11.

$1\text{C}7_{16}$ (by grouping into nibbles: $0001 = 1$, $1100 = \text{C}$, $0111 = 7$).

How is octal $62_8$ converted to binary by dividing digits individually?

$6_8 = 110_2$ and $2_8 = 010_2$, combining to make $110010_2$.

How is octal $714_8$ converted to binary?

$111001100_2$ (since $7_8 = 111_2$, $1_8 = 001_2$, and $4_8 = 100_2$).

What is the decimal equivalent of octal $536_8$?

$350_{10}$ (via binary $101011110_2$: $256 + 64 + 16 + 8 + 4 + 2 = 350$).

What is the base of the Hexadecimal number system, and what range of values does it accept?

Base $16$; accepts $16$ values from $0$ to $15$.

In hexadecimal representation, which numbers are used directly and which are represented by letters?

$0\text{--}9$ are represented directly; $10\text{--}15$ are represented by letters $A\text{--}F$.

What are the exact decimal values assigned to hexadecimal letters $A$ through $F$?

$A = 10$, $B = 11$, $C = 12$, $D = 13$, $E = 14$, $F = 15$.

Convert the binary byte $00101101_2$ to hexadecimal.

$2\text{D}_{16}$ ($0010_2 = 2$ and $1101_2 = 8 + 4 + 0 + 1 = 13 = \text{D}$).

Convert the binary byte $11011100_2$ to hexadecimal.

$\text{DC}_{16}$ ($1101_2 = 8 + 4 + 0 + 1 = 13 = \text{D}$ and $1100_2 = 8 + 4 + 0 + 0 = 12 = \text{C}$).

Convert hexadecimal $7\text{B}_{16}$ into binary.

$01111011_2$ ($7 = 0111_2$ and $\text{B} = 11 = 1011_2$).

What are Alpha-numeric keys on a keyboard?

Standard $A\text{--}Z$ letters and $0\text{--}9$ numbers.

What are Modifier keys, and what examples are given?

Keys that don't do much on their own but change the function of other keys when pressed together; examples include Shift, Ctrl, and Alt.

What are Function keys, and where are they located?

Keys located at the top of the keyboard ($\text{F}_1\text{--}\text{F}_{12}$) that perform specific tasks depending on the software you're using.

What are Navigation keys, and what examples are listed?

Keys that help you move around a document or interface; examples include Arrow keys, Home, End, Page Up, and Page Down.

What are System / command keys on a keyboard, and what examples are given?

Keys that perform specific system-level actions; examples include Print Screen, Delete, Backspace, and Enter.

What is the purpose of the Numeric keypad?

A separated cluster of numbers on the right side of the keyboard for faster data entry.

What are the eight main functions of utility software listed in Source 15?

1. Detects and removes viruses and other malware; 2. Removes unnecessary files to free up storage space; 3. Reduces file sizes to save storage space; 4. Creates copies of files to prevent data loss; 5. Helps recover lost/deleted files; 6. Detects and sometimes repairs disk errors; 7. Helps improve computer performance; 8. Protects data by converting it into a form that an unauthorized user cannot read (encryption).

What are eight functions of an Operating System detailed in Source 15?

1. Controls execution of programs; 2. Organizes, stores, retrieves and deletes files; 3. Monitors the use of system resources; 4. Allows application software to run; 5. Distributes computer resources among running programs; 6. Protects the computer and its data from unauthorized access; 7. Controls input and output devices; 8. Allocates and manages the computer's main memory (RAM).

What are the first three immediate steps to deal with a computer infected by malware?

1. Turn off Wi-Fi / unplug the network cable to prevent the malware from communicating with other systems; 2. Run an antivirus scan using trusted antivirus software (i.e., Microsoft Defender) to detect and remove malware; 3. Isolate suspicious files so that they cannot harm the computer.

What further remediation actions should be taken after isolating malware on an infected computer?

Install security updates to fix vulnerabilities, remove malicious applications, recover damaged or missing files from a clean backup, change passwords for compromised accounts, and perform another full scan to confirm removal.

What are preventive measures to protect a computer from malware infection?

Install antivirus software, update OS regularly to fix irregularities, use a firewall to prevent unauthorised access, avoid suspicious links, scan external storage devices before opening, download software from trusted sources, use strong passwords, back up important data, and use genuine software.

Why should users use genuine software rather than pirated software?

Because pirated software may contain malware.

How do worms and viruses differ regarding self-sufficiency and human action?

A worm can spread automatically without user action and is a standalone program, whereas a virus attaches itself to a host program or file and requires user interaction with an infected file to spread.

How do worms and viruses differ in their transmission medium and system impact?

Viruses spread when infected files/programs are shared or executed and infect/modify files; worms spread through computer networks and consume network bandwidth and system resources.