Hardware and Software

Definitions

• Hardware: The physical components of a computer system, such as the CPU, memory, storage devices, and input/output devices.

• Software: The programs and operating information used by a computer. Software can be divided into system software and application software.

Relationship Between Hardware and Software

• Hardware requires software to perform tasks. Software provides the instructions that tell the hardware what to do. Without software, hardware is non-functional; without hardware, software cannot run.

System Software and Application Software

System Software

• Software designed to manage and control the hardware components and provide a platform for running application software.

  • Examples: Operating systems (e.g., Windows, macOS, Linux), utility programs (e.g., antivirus software, disk management tools).

Application Software

• Software designed to help users perform specific tasks.

  • Examples: Word processors (e.g., Microsoft Word), web browsers (e.g., Google Chrome), games, and business applications.

Operating System (OS) and Utility Programs

Need for OS

• Manages hardware resources, provides a user interface, and serves as a platform for running application software.

• Process management, memory management, file system management, device management, and security.

Utility Programs

• Function: Perform maintenance tasks to ensure the smooth operation of the computer system.

  • Examples: Disk cleanup, backup software, antivirus programs, file compression tools.

Logic Gates and Truth Tables

Basic Logic Gates

• NOT Gate: Inverts the input.

• AND Gate: Outputs true if both inputs are true.

• OR Gate: Outputs true if at least one input is true.

• XOR Gate: Outputs true if exactly one input is true.

Constructing Truth Tables

• NOT Gate:

  A	NOT A
  0	1
  1	0

• AND Gate:

  A	B	A AND B
  0	0	0
  0	1	0
  1	0	0
  1	1	1

• OR Gate:

  A	B	A OR B
  0	0	0
  0	1	1
  1	0	1
  1	1	1

• XOR Gate:

  A	B	A XOR B
  0	0	0
  0	1	1
  1	0	1
  1	1	0

Constructing and Interpreting Logic Circuits

• Simple Logic Circuits: Combine multiple gates to perform complex operations. Construct truth tables for these circuits to understand their behavior.

  • Example:

    • Circuit: (A AND B) OR (NOT C)

Truth Table:

Boolean Expressions and Logic Circuits

• Creating Boolean Expressions: Write expressions using NOT, AND, OR, and XOR to represent logic circuits.

• Example: For the circuit above, the Boolean expression is (A AND B) OR (NOT C) (A AND B) OR (NOT C) (A AND B) OR (NOT C).

• Converting Boolean Expressions to Circuits: Draw the logic gates that represent the Boolean expression.

Low-Level and High-Level Languages

Differences

• High-Level Languages: Easier for humans to read and write (e.g., Python, Java). Abstracted from hardware details.

• Low-Level Languages: Closer to machine code, more control over hardware (e.g., assembly language).

Low-Level Languages

• Assembly Language: Human-readable form of machine code, uses mnemonics.

• Machine Code: Binary code specific to a processor.

Translation of Languages

• High-level and assembly languages must be translated into machine code for the CPU to execute.

• Methods:

  • Compilers: Translate high-level code into machine code before execution.

  • Interpreters: Translate and execute high-level code line by line.

  • Assemblers: Translate assembly language into machine code.

Machine Code

• Expressed in Binary: Uses binary (0s and 1s) to represent instructions and data.

• Processor-Specific: Different processors have different machine code instructions.

Advantages and Disadvantages

• High-Level Languages:

  • Advantages: Easier to learn, write, and maintain; portable across different systems.

  • Disadvantages: Less control over hardware, may be less efficient.

• Low-Level Languages:

  • Advantages: Greater control over hardware, can be more efficient.

  • Disadvantages: Harder to learn, write, and maintain; specific to a processor family.

Interpreters, Compilers, and Assemblers

Interpreters

• Function: Translate and execute code line by line.

• When to Use: During development for quick testing and debugging.

• Advantages: Immediate error detection, no need for recompilation.

• Disadvantages: Slower execution speed compared to compiled code.

Compilers

• Function: Translate the entire program into machine code before execution.

• When to Use: For production code to achieve faster execution.

• Advantages: Optimized code, faster execution.

• Disadvantages: Compilation can be time-consuming, harder to debug.

Assemblers

• Function: Translate assembly language into machine code.

• When to Use: When low-level programming and hardware control are required.

• Advantages: Efficient, gives control over hardware.

• Disadvantages: Assembly language is complex and time-consuming to write.