Introduction to Computers and Programming

Introduction to Computers and Programming

• Computers are programmable devices designed to follow instructions.
• A program is a set of instructions that the computer follows to complete a task, also known as software.
• A programmer is someone who designs, creates, and tests programs, commonly referred to as a software developer.

Hardware and Software

• Hardware: Physical components of a computer system.
  • Major components include:
  • Central Processing Unit (CPU): Executes programs and is crucial for running software.
  • Main Memory (RAM): Temporary storage that holds programs and data while the computer is on (volatile).
  • Secondary Storage: Long-term data storage, including disk drives and solid-state drives (SSD).
  • Input Devices: Components that collect data (e.g., keyboard, mouse).
  • Output Devices: Components that present data (e.g., monitor, printer).

The CPU

• The CPU is the core of the computer that executes programs.
• Historically large but now found on microprocessors, which are compact and efficient.

Main Memory

• RAM allows the CPU to quickly access data while programs are running.
• Data in RAM is lost when the computer is powered off.

Secondary Storage Devices

• Secondary storage retains data for extended periods.
  • Disk Drive: Uses magnetic encoding on spinning disks.
  • Solid State Drive (SSD): Faster, with no moving parts, using solid state memory.
  • Flash Memory: Portable and also uses solid state technology.

Data Input and Output

• Input: Data collected by the computer, which can be from humans or other devices.
• Output: The data processed by the computer for display or distribution, which can be text, images, or sounds.

Software Overview

• Software controls all computer operations:
  • Application Software: Programs for everyday tasks (e.g., word processing, web browsing).
  • System Software: Manages hardware operations, including operating systems and utilities.

How Computers Store Data

• Data is represented as sequences of 0s and 1s (binary system).
• A byte can store one character and consists of 8 bits.
• Each bit can be a 0 or a 1; thus, a byte can represent values from 0 to 255.

Storing Different Types of Data

• Numbers: Binary representation allows encoding numbers, with larger values requiring more bytes.
• Characters: Stored as binary using encoding schemes like ASCII (limited to 128 characters) and Unicode (which supports many languages).
• Negative and Real Numbers: Negative numbers are stored using two’s complement; real numbers use floating-point notation.
• Digital Data: Images and music are stored as binary values representing pixels and audio samples, respectively.

How a Program Works

• The CPU performs operations using machine language.
• A program must be loaded into RAM, and the CPU processes it through the fetch-decode-execute cycle:
  • Fetch: Reads the next instruction into the CPU.
  • Decode: Interprets the instruction to determine the operation.
  • Execute: Carries out the operation.

Programming Languages

• Assembly Language: Easier alternative to machine language that uses mnemonic codes.
• High-Level Languages: Simplifies programming without needing detailed CPU knowledge.

Compilers and Interpreters

• Programs in high-level languages require translation to machine code:
  • Compiler: Translates the entire program at once, creating an executable file.
  • Interpreter: Translates and executes one instruction at a time, used by languages like Python.

Using Python

• Python requires installation, including its interpreter.
• Modes of execution in Python:
  • Interactive Mode: Direct input and immediate output.
  • Script Mode: Save commands in a file with a .py extension and run them from the command line.

IDLE Programming Environment

• IDLE: Provides tools to write and execute Python programs, featuring a text editor for coding.

Summary of Chapter

• This chapter discussed:
  • Main hardware components of a computer.
  • Types of software and how data is stored.
  • Basic CPU operations and the fetch-decode-execute cycle.
  • The necessity of compiling or interpreting code and using Python effectively.