Computer Systems Basics

Computer Systems

• A computer is an electronic device that takes input, processes it, stores data, and produces output.

Fixed vs Programmable Computers

• Fixed computers perform a specific task and cannot be programmed to do anything else.
• Programmable computers can be programmed to perform a variety of tasks.

Calculators vs Computers

• Calculators are special-purpose computers that perform mathematical calculations.
• Computers are general-purpose devices that can perform various tasks beyond calculations.

Input and Output

• Input devices: keyboard, mouse, scanner, microphone, etc.
• Output devices: monitor, printer, speaker, etc.

RAM vs ROM

• RAM (Random Access Memory) is volatile memory that temporarily stores data and program instructions while the computer is running.
• ROM (Read-Only Memory) is non-volatile memory that permanently stores data and cannot be changed.

Secondary Storage

• Secondary storage is necessary because RAM is volatile and limited in capacity.
• Types of secondary storage: hard disk drives, solid-state drives, magnetic tapes, CDs, DVDs, Blu-ray discs.
• Technologies used: magnetic, optical, solid-state.

CPU (Central Processing Unit)

• Parts of a CPU:
  • ALU (Arithmetic Logic Unit): performs mathematical and logical operations.
  • Busses: connect different parts of the CPU.
  • Clock: generates a synchronizing signal.
  • Registers: small amount of on-chip memory.
  • Control Unit: retrieves and executes instructions.

Operating System

• Roles of an operating system:
  • Managing Memory: allocating memory to programs.
  • Program Execution: loading and executing programs.
  • Managing Input/Output: interacting with devices.
  • Managing User Interface (GUI): providing a Graphical User Interface.
  • Managing Communication: controlling communication between devices and the computer.

Binary System

• Binary is a number system with base 2, using only 0s and 1s.
• Converting Denary to Binary:
  • Divide the denary number by 2 and note the remainder.
  • Repeat step 1 until the quotient is 0.
  • The binary representation is the sequence of remainders in reverse order.
• Converting Binary to Denary:
  • Multiply each binary digit (starting from the right) by 2 to the power of its position (starting from 0).
  • Add the products to obtain the denary equivalent.

Binary Maths

• Adding three binary numbers together:
  • Perform binary addition for each column (right to left).
  • Carry over any overflow to the next column.

Data Sizes

• Bit: a single binary digit.
• Nibble: a group of 4 bits.
• Byte: a group of 8 bits.
• Kilobyte (KB): 1024 bytes.
• Megabyte (MB): 1024 KB.
• Gigabyte (GB): 1024 MB.
• Terabyte (TB): 1024 GB.