Computer Basics and Hardware Overview

Study Notes

A computer is an electronic device that processes data according to a set of instructions called a program.
Computers are categorized as analog, digital, or hybrid.
Digital computers are further classified by size and power: embedded, mobile, personal, midrange servers, mainframe, and supercomputer.

Hardware refers to the physical components of a computer.
The Central Processing Unit (CPU) is the brain of the computer, responsible for executing instructions.
The CPU consists of three main parts:
- Arithmetic Logic Unit (ALU) performs arithmetic and logical operations.
- Control Unit controls data movement and instruction execution.
- Registers are small, high-speed storage areas.
Memory is used for data storage.
- Primary memory (RAM and ROM) is directly accessible by the CPU.
- Secondary memory (hard disk, DVD, USB, etc.) provides permanent long-term storage and is not directly accessed by the CPU.
Input devices allow users to enter data into the computer (e.g., keyboard, mouse, webcam, microphone).
Output devices display or communicate processed data from the computer (e.g., monitor, printer, speakers).

Software refers to the programs or instructions that tell the computer hardware what to do.
Computer programming involves creating a sequence of instructions for the computer to execute.
Software is classified into two main categories:
- System software: programs designed to operate and control computer hardware and run application programs.
- Application software: programs designed for end-users to perform specific tasks (e.g., word processing, spreadsheets, web browsing).

Programming languages are similar to human languages, using specific syntax and reserved keywords.
They are categorized by their level of abstraction:
- Machine language: uses binary code (1s and 0s) to create machine-dependent instructions.
- Assembly language: uses mnemonics (English-like terms) to create instructions, also machine-dependent.
- High-level languages: use a more human-readable syntax, are portable and often include languages like Cobol, Basic, C, C++, C#, Java.

An operating system is a type of system software that manages and controls the computer's hardware.
It runs other programs on the computer and interfaces with the user.
Operating systems are responsible for tasks such as file management, memory management, and handling input/output.
Common examples of operating systems include DOS, Windows, Unix, Linux, and Mac OSX.

The program development life cycle (PDLC) outlines the steps involved in creating and maintaining software.
The steps are:
- Problem Definition: Clearly define the problem to be solved.
- Problem Analysis: Understand the problem thoroughly to develop a viable solution.
- Algorithm Development: Create a step-by-step procedure to solve the problem.
- Coding: Write the program using a chosen programming language.
- Testing & Debugging: Ensure the program produces the desired output and identify/fix any errors.
- Maintenance: Ongoing support and updates to the program based on user feedback and evolving needs.

Two common methods are used to specify algorithms:
- Pseudocode: Uses natural language (e.g., English) to describe the algorithm steps.
- Flowchart: Uses a diagram to illustrate the flow of the program steps.

Translators convert programming code into machine-executable code.
Types include:
- Assembler: Converts assembly language into machine code.
- Interpreter: Converts a high-level language into machine code line-by-line.
- Compiler: Converts an entire high-level language program into machine code (an executable file).

Also known as modular programming, it focuses on logical structure rather than data.
Uses a top-down approach, breaking programs into smaller, logically structured blocks of code called functions.
Each function performs a specific task, making programs easier to understand and modify.