Computing Systems and Networks - Vocabulary

Computer Numbering Systems

• Bit: Short for Binary Digit; fundamental unit of computer data, represented as $0$ or $1$.

• Byte: Group of $8$ bits ($1\,\text{byte}$) representing a single character.

• Denary (Decimal): Base-$10$ system using digits $0$–$9$; place values increase by powers of $10$ ($10^0$, $10^1$, $10^2$).

• Binary: Base-$2$ system using digits $0$ and $1$; place values increase by powers of $2$ ($2^0$, $2^1$, $2^2$).

Character Encoding and ASCII

• ASCII: Standard $8$-bit character code mapping text and symbols to binary:

  • Space = Denary $32$ = Binary $00100000$

  • Symbol # = Denary $35$ = Binary $00100011$

  • Digit 0 = Denary $48$ = Binary $00110000$

  • Digit 9 = Denary $57$ = Binary $00111001$

  • Letter A = Denary $65$ = Binary $01000001$

  • Letter a = Denary $97$ = Binary $01100001$

Hexadecimal System

• Base-$16$ system using digits $0$–$9$ and letters $A$–$F$ ($A = 10$, $B = 11$, $C = 12$, $D = 13$, $E = 14$, $F = 15$).

• Compact, human-readable format for binary values used in memory addressing and web color codes.

Network Communication and Geographic Types

• Internet: Global network of interconnected networks using standard protocols; no single owner.

• Network Classifications:

  • LAN (Local Area Network): Small physical area (e.g., single classroom or building).

  • MAN (Metropolitan Area Network): City-wide area (e.g., municipal traffic camera systems).

  • WAN (Wide Area Network): Spans national or global distances (e.g., the Internet).

Signal Transmission Media

• Copper Cable: Transmits electrical signals.

• Fibre Optic Cable: Transmits optical signals (light pulses).

• Wireless Transmission: Transmits radio wave signals through air space.

• Interference: External electromagnetic or physical disruption degrading signals.

Bandwidth, Throughput, and Latency

• Bandwidth: Theoretical maximum data transmission capacity per second, measured in bits per second ($\text{bps}$).

  • Conversion Units: $1\,\text{Kbps} = 1,000\,\text{bps}$, $1\,\text{Mbps} = 1,000\,\text{Kbps}$, $1\,\text{Gbps} = 1,000\,\text{Mbps}$, $1\,\text{Tbps} = 1,000\,\text{Gbps}$.

• Throughput: Actual rate of successful data delivery across a network.

• Latency: Time delay experienced as data travels from source to destination.

Network Architectural Models

• Client-Server Model:

  • Centralized servers deliver services and resources to client endpoints.

  • Pros: Centralized administration, strong security, high scalability.

  • Cons: Expensive setup, server collapse creates a single point of failure.

• Peer-to-Peer (P2P) Model:

  • Devices act as equal peers, simultaneously serving and requesting data.

  • Pros: Low cost, simple setup, no central point of failure.

  • Cons: Weak security, poor scalability, reduced device performance.

Infrastructure Categories and Network Topologies

• Infrastructure Categories: End devices (hosts), intermediate devices (routers/switches), and network media.

• Topologies:

  • Star: Endpoints connect to a single central switch or hub.

  • Bus: All devices connect along a single shared physical cable.

  • Ring: Devices connect sequentially in a circular loop.

  • Mesh: Devices are redundantly interconnected with multiple direct links.