Chapter 1 Summary: Introduction to Computers and Programming

Introduction

• Computers are programmable and execute instructions from programs (software).

• Programmers design, create, and test these programs.

Hardware and Software

• Hardware: Physical components of a computer (CPU, memory, storage, input/output devices).

• Software: Programs that control the computer.

Components of Hardware

• CPU (Central Processing Unit): Runs programs; located on microprocessors.

• Main Memory (RAM): Temporary, volatile storage for running programs and data.

• Secondary Storage: Long-term data storage (disk drives, solid-state drives, flash memory).

• Input Devices: Collect data (keyboard, mouse, etc.).

• Output Devices: Present data (video display, printer, etc.).

Types of Software

• Application Software: For everyday tasks (word processing, web browsing).

• System Software: Manages computer operations.

  • Operating System: Controls hardware.

  • Utility Programs: Enhance operation/safeguard data.

  • Software Development Tools: Create/modify software.

How Computers Store Data

• Data is stored as sequences of 0s and 1s.

• Bit: Electrical component holding positive or negative charge.

• Byte: 8 bits; stores a letter or small number.

• Binary numbering system is used; position j has value 2^{j-1}.

• Characters are converted to numeric codes (ASCII, Unicode).

• Negative numbers use two’s complement; real numbers use floating-point notation.

• Digital images are stored as pixels (binary numbers representing color); digital music as samples (binary numbers).

How a Program Works

• CPU performs simple operations using machine language.

• Program execution cycle: Fetch (instruction from memory), Decode (determine operation), Execute (perform operation).

Languages

• Assembly Language: Uses mnemonics; translated to machine language by an assembler.

• High-Level Language: More intuitive; doesn't require knowledge of CPU operation.

• Keywords: Predefined words in high-level languages.

• Operators: Perform operations on data.

• Syntax: Rules for writing programs.

• Statement: Individual instruction.

Compilers and Interpreters

• Compiler: Translates high-level to machine language.

• Interpreter: Translates and executes one instruction at a time (used by Python).

• Source code: Statements written by programmer.

• Syntax error: Prevents code translation.

Using Python

• Python interpreter can be used in interactive mode (statements entered on keyboard) or script mode (statements saved in a .py file).

• IDLE: Integrated Development Environment for writing, executing, and testing Python programs. Runs in interactive mode and has a text editor.