Computer Fundamentals and Binary Systems

Computer Block Diagram

• CPU (Central Processing Unit)

  • ALU (Arithmetic and Logical Unit): Performs arithmetic and logical operations.

    • Arithmetic operations: addition, subtraction, multiplication, division, modulus.

    • Logical operations: compare (equal, greater than), AND, OR, NOT.

  • CU (Control Unit): Utilizes other resources; controls the hard disk drive, main memory, input and output devices.

• Main Memory: Working memory, primary memory, or workspace.

• Hard Disk Drive: Contains data in the form of files.

  • Program files (e.g., Notepad.exe).

  • Data files (e.g., my.txt, audio files, video files).

• Input Devices: Keyboard, mouse, stylus tablet.

• Output Devices: Monitor, printer, speakers.

Program Execution

• Programs from the hard disk are loaded into the main memory.

• The CPU executes the program by fetching instructions line by line.

• Programs interact with users through input and output devices.

• Input/Output Buffers: Input devices have an input buffer and output devices have an output buffer, which serve as communication points between the device and the program.

• Data from the keyboard goes into the input buffer, and the program reads from it.

• Data to the monitor goes into the output buffer (frame buffer), which is then displayed on the screen.

Binary Number System

• Computers operate using a binary number system because they are electronic devices working on current or voltages.

• Low voltage = 0, High voltage = 1.

• Analogy: A bulb can be either off (0) or on (1).

• Integrated Circuits (ICs) or Chips:

  • Have pins that can pass voltages (either low or high).

  • Each pin represents 1 bit.

• 1 bit: A single binary digit (0 or 1).

• 8 bits: Referred to as 1 byte.

• 8 bits can form various patterns (e.g., 00000000, 00000001).

Instructions as Bit Patterns

• Each pattern of bits can be interpreted as an instruction.

• Example: 1 bulb can give 2 messages (on or off).

• Traffic signal analogy: Bulb on = go, Bulb off = stop.

• Increasing Bulbs:

  • 2 bulbs: $2^2 = 4$ different messages.

  • 3 bulbs: $2^3 = 8$ different messages.

  • 4 bulbs: $2^4 = 16$ different messages.

  • 8 bulbs: $2^8 = 256$ different messages/commands.

Computer Language

• Computers understand binary language (0s and 1s).

• All instructions and data are represented in binary.

• Arithmetic and logical operations are performed on binary numbers.

Decimal vs. Binary Number Systems

• Decimal system: digits from 0 to 9.

• Binary system: digits 0 and 1.

• Examples:

  • Decimal 0 = Binary 0

  • Decimal 1 = Binary 1

  • Decimal 2 = Binary 10

  • Decimal 3 = Binary 11

  • Decimal 4 = Binary 100

  • Decimal 5 = Binary 101

CPU Instructions

• CPU knows predefined instructions (e.g., 0 means add, 1 means subtract).

• Instructions are in the form of binary codes.

• Programs in main memory are in binary form.

• CPU executes programs by interpreting each line (instruction) based on its binary code.

Conclusion

• Computers work on the binary number system because they are based on electronics.

• Electronic signals are either 0 or 1 (low or high voltage).

• Number systems will be discussed in future videos.