Introduction to Computer Systems

What is a Computer?

• A computer is an electronic device that can store, process, and communicate information.

Fixed vs Programmable Computers

• Fixed computers: designed to perform a specific task and cannot be changed.
• Programmable computers: can be programmed to perform different tasks and can be modified.

Calculators vs Computers

• Calculators: electronic devices designed to perform mathematical calculations.
• Computers: electronic devices that can perform a wide range of tasks, including calculations, processing, and communication.

Input and Output

• Inputs: devices that allow users to enter data or instructions into the computer, such as keyboards, mice, and scanners.
• Outputs: devices that display or produce the results of the computer's processing, such as monitors, printers, and speakers.

RAM vs ROM

• RAM (Random Access Memory): temporary storage for data and programs that the computer is currently using.
• ROM (Read-Only Memory): permanent storage for data and programs that do not change, such as the computer's BIOS.

Secondary Storage

• Necessary because RAM is volatile and limited in capacity.
• Types of secondary storage: hard drives, solid-state drives, flash drives, magnetic tapes, and optical discs.
• Technologies used: magnetic, optical, and solid-state.

CPU

• ALU (Arithmetic Logic Unit): performs mathematical calculations and logical operations.
• Busses: pathways for data and instructions to move between different parts of the computer.
• Clock: regulates the timing of the computer's operations.
• Registers: small amounts of memory built into the CPU to store temporary results.
• Control Unit: retrieves and executes instructions, manages data flow.

Operating System

• Role: manages memory, executes programs, manages input and output, manages user interface (GUI), and manages communication.
• Manages memory by allocating and deallocating space for programs and data.
• Executes programs by loading and running them in the CPU.
• Manages input and output by controlling the flow of data between devices and the CPU.
• Manages user interface by providing a visual interface for users to interact with the computer.
• Manages communication by controlling the flow of data between the computer and other devices.

Binary

• A binary number system that uses only two digits: 0 and 1.
• Can be converted from and to denary (decimal) numbers.

Converting Denary to Binary

• Example: 12 (denary) = 1100 (binary)

Converting Binary to Denary

• Example: 1100 (binary) = 12 (denary)

Binary Maths

• Can add three binary numbers together using the rules of binary arithmetic.

Data Sizes

• Bit: the smallest unit of data, representing a single binary digit.
• Nibble: a group of 4 bits, often used to represent a single hexadecimal digit.
• Byte: a group of 8 bits, often used to represent a single character or number.
• Kilobyte (KB): 1024 bytes.
• Megabyte (MB): 1024 kilobytes.
• Gigabyte (GB): 1024 megabytes.
• Terabyte (TB): 1024 gigabytes.