Computer Systems Overview

Computer Systems Overview

• A computer system is a collection of interconnected components working together to process data and generate output.
• Key components include the CPU, memory, storage, and input/output (I/O) devices.

Von Neumann Architecture

• A conceptual model for computer systems, first proposed in the 1940s.
• Four-stage process: Fetch, Decode, Execute, Store.

CPU

• Stands for central processing unit.
• The "brain" of the computer system, responsible for processing data and instructions.
• Main components: Control Unit and Arithmetic Logic Unit (ALU).
• Arithmetic Logic Unit (ALU) performs arithmetic and logical operations.

Registers

• High-speed storage locations used by the CPU to store data and instructions.
• Faster than main memory (RAM).
• Different types with specific purposes: general-purpose, special-purpose (e.g., program counter).

Program Counter (PC)

• Stores the address of the next instruction to be executed.
• Incremented after each instruction.

Memory

• Stores data and instructions needed by the CPU.
• Typically slower than registers.
• Types: RAM (volatile) and ROM (non-volatile).

Input/Output Devices (I/O)

• Allow the computer to interact with the external world.
• Input devices allow user input (e.g., keyboard, mouse).
• Output devices display or produce data (e.g., monitor, printer).

Motherboard

• The main circuit board of a computer.
• Connects all other components (CPU, memory, storage, I/O devices).

Secondary Storage

• Non-volatile memory; stores data even when the computer is turned off.
• Examples: hard drives, solid-state drives, optical discs, magnetic tape.

Fetch-Execute Cycle

• The process by which the CPU executes instructions.
• Four stages: Fetch, Decode, Execute, Store.

Clock

• Generates regular pulse signals to synchronize instruction execution.
• Speed is measured in Hertz (Hz). A faster clock speed typically means a faster CPU.

Bus

• A set of electrical wires allowing components to communicate.
• Three types: Data lines, Address lines, Control lines.

Binary Code & Electrical Signals

• Binary code uses 0s and 1s to represent information.
• Electrical signals, such as high voltage (1) and low voltage (0), represent binary values.

Electricity and Electrons

• Electricity is the flow of electrons.
• Electrons are negatively charged particles.
• The flow of electrons is electric current.
• Voltage represents the electrical potential difference between points in a circuit.

Electric Current

• Rate of flow of electric charge through a conductor.
• Measured in amperes (amps).

Voltage

• Electrical potential difference between two points in a circuit.
• Measured in Volts.
• Higher voltage signals typically represent stronger signals

Transistors

• Semiconductor devices used for amplification and switching electronic signals
• Fundamental building blocks in CPUs (central processing units)
• Used in logic gates

Resistors and Resistance

• Electrical components that restrict current flow.
• Measured in ohms (Ω).
• Varying resistance allows control of current flow.

Capacitors

• Store electrical energy.
• Used in filtering and smoothing electrical signals and storing energy.

Logic Gates

• Basic building blocks of digital circuits.
• Implement simple logical operations (AND, OR, NOT, etc.)
• Constructed using transistors.
• Used by the CPU during the fetch-execute cycle and for arithmetic/logic operations

Operating Systems

• Software managing hardware and software resources.
• Main functions: booting, managing memory, CPU, I/O devices, and providing system services.
• Structure layers for hardware, operating system, applications, and user interaction

Web Infrastructure

• Internet a global system of interconnected computer networks using TCP/IP.
• Terms/concepts: IP address, URL, HTTP, HTTPS, DNS, TCP/UDP.
• Client-server model for resource distribution.
• Benefits include scalability, reliability, security.

Communication Protocols

• Rules dictating device communication.
• Examples: HTTP, HTTPS, TCP, UDP.

WiFi

• Wireless networking technology using radio waves to connect devices to the internet.

VoIP

• Voice over Internet Protocol; transmits voice calls digitally over the internet.

Gateways

• Connect two networks using different protocols.

Routers

• Forward data packets between networks based on IP addresses.

Network Bridges

• Connect two LANs with the same protocol.

Network Switches

• Connect multiple devices on a LAN to improve performance.

Repeaters

• Amplify and retransmit data signals to extend network reach.

Cloud Computing

• On-demand computing services over the internet.
• Categories: IaaS, PaaS, SaaS