Topic 6: Fundamentals of Computer Systems

Hardware

The physical components of a computer system that can be touched[cite: 36].

Software

Program code consisting of sequences of instructions executed to perform a task[cite: 36].

System Software

Software that operates, controls, and maintains the computer and its components, including operating systems, utilities, libraries, and translators[cite: 37].

Application Software

Programs that complete a specific user task, such as word processors or web browsers[cite: 37].

Operating System (OS)

System software that provides a virtual machine to hide hardware complexity and manages resources like memory, processor scheduling, and interrupts[cite: 37].

Utility Programs

System software used for housekeeping tasks such as data backup, hard drive defragmentation, data compression, and encryption[cite: 37].

Library Programs

Collections of useful, frequently used functions that programmers can import when developing code[cite: 38].

Translators

Software programs that translate between different types of languages, specifically compilers, assemblers, and interpreters[cite: 38].

Machine Code

A low-level language using binary digits (1s and 0s) that directly manipulates the processor and is processor-specific[cite: 41, 44].

Assembly Language

A low-level language using mnemonics (e.g., ADD, MOV) with a 1-to-1 correlation to machine code instructions[cite: 42].

High-Level Language

A programming language using English-like instructions (e.g., Python, C#) that is portable and not processor-specific[cite: 43].

Imperative High-Level Language

A high-level language formed from instructions that specify *how* the computer should complete a task[cite: 43].

Assembler

A translator that converts assembly language into machine code with a 1-to-1 instruction correlation[cite: 47].

Compiler

A translator that checks entire high-level source code for errors and translates it all at once into machine code[cite: 47, 48].

Interpreter

A translator that checks and executes high-level source code line-by-line sequentially[cite: 47, 48].

Intermediate Language / Bytecode

An intermediate code format produced by some compilers that enables platform independence via a virtual machine[cite: 48].

Source Code

The input code provided to a translator, written in assembly or a high-level language[cite: 48].

Object Code

The output code produced by a translator from source code[cite: 48].

Logic Gates

Devices that apply logical operations to one or more Boolean inputs in order to produce a single output[cite: 22].

NOT Gate

A logic gate with one input whose output is always the opposite of its input[cite: 22].

AND Gate

A logic gate with two inputs that outputs TRUE (1) only when both inputs are TRUE[cite: 23].

OR Gate

A logic gate that outputs TRUE if one or more of its inputs are TRUE[cite: 23].

XOR Gate (Exclusive OR)

A logic gate that outputs TRUE when strictly one of its inputs is TRUE[cite: 24].

NAND Gate

A combination of an AND gate followed by a NOT gate, outputting the reverse of an AND gate[cite: 24].

NOR Gate

A combination of an OR gate followed by a NOT gate, outputting the reverse of an OR gate[cite: 25].

Half Adder

A logic circuit with two inputs (A, B) and two outputs (Sum, Carry) used to add two Boolean values[cite: 28].

Full Adder

A logic circuit with three inputs (A, B, and Carry-in) and two outputs (Sum and Carry-out) enabling addition with a carry bit[cite: 29].

Edge-Triggered D-Type Flip-Flop

A logic circuit used as a memory unit for storing the value of a single bit, updated with each change of a clock signal[cite: 30].

Boolean Algebra Order of Precedence

The order of evaluation from highest to lowest precedence: Brackets, NOT, AND, OR[cite: 33].

Boolean Identity (AND with 0)

$A \cdot 0 = 0$, because anything AND 0 is always 0[cite: 34].

Boolean Identity (OR with 1)

$A + 1 = 1$, because anything OR 1 always results in 1[cite: 34].

Double Negation Identity

$\bar{\bar{G}} = G$, meaning performing the NOT operation twice leaves the value unchanged[cite: 34].

De Morgan's Laws

Rules for simplifying Boolean expressions summarised by the phrase "break the bar and change the sign" (e.g., $\overline{A+B} = \bar{A} \cdot \bar{B}$)[cite: 35].