INSIDE COMPUTERS Lecture 2

Outlines

• How data are represented in Computers?

• Digital Data Representation

• Representing Text, Numbers, Graphics, Audio, and Video Data

• Inside the System Unit

• Basic Computer Hardware components

• CPU & GPU Processors

• Cache Memory and Bus Bandwidth

• Main & Secondary Memory

• Hard Drives and Optical Discs

• Flash Memory & Magnetic Tape

• Future Trends

How Data are Represented in Computers

• Data and programs must be suitably represented to be understood by a computer.

• Coding systems: Represent data and programs in a computable format.

• Computers consist of switches with two states: ON (1) and OFF (0).

Digital Data Representation

• Bit: Smallest data unit recognized by a binary computer (1 or 0).

• Byte: Consists of 8 bits; used to express size of files.

Data Size Prefixes

• Kilobyte (KB) = 210 bytes (1024 bytes)

• Megabyte (MB) = 220 bytes (1024 KB)

• Gigabyte (GB) = 230 bytes (1024 MB)

• Terabyte (TB) = 240 bytes (1024 GB)

• Larger units: Petabyte (PB), Exabyte (EB), Zettabyte (ZB), Yottabyte (YB).

Representing Text

• Each character receives a unique bit pattern.

• ASCII: 7-bit standard for most English text.

• Extended ASCII: 8-bit variations for major language groups.

• Unicode: Universal standard using 32 bits per character.

Representing Numeric Values

• Numbering System: Method for representing numbers.

• Binary notation: Uses bits for base two representation.

  • Binary: Base 2.

  • Decimal: Base 10.

Decimal Numbers

• Use digits 0-9 in a positional system.

• Weight formula: Weight = Base^Position.

Binary Numbers

• Uses digits 0 and 1.

• Positional representation includes weights based on powers of 2.

Representing Graphics

• Bitmapped images use various bit depths (4, 8, 24 bits); more bits = more colors.

• GIF: 8 bits per pixel (up to 256 colors).

• JPEG: 24 bits per pixel (better color representation).

• PNG: Supports various bit-depths.

Representing Audio and Video Data

• Audio data needs digital format (e.g., MP3 for compression).

• Video is a series of frames and can be compressed for efficiency.

Inside the System Unit

• CPU: Performs calculations and comparisons.

• Power Supply: Converts electrical power into a usable form.

• Fan: Cools the CPU.

• Hard Drive: Main storage for data and programs.

• Motherboard: Connects all components.

• Memory Slots: Support various storage formats.

Basic Computer Hardware Components

• Computer chip: Silicon piece with integrated circuits.

• Motherboard: Main circuit board.

• CPU: Main processing unit; microprocessor.

• Dual-core/Quad-core CPU: Multiple processors on a single chip.

GPU Processors

• Graphics Processing Unit (GPU): Specialized for image creation.

• Used in PCs, embedded systems, and gaming consoles.

Cache Memory and Bus Bandwidth

• Cache Memory: Fast memory close to the CPU (Levels 1, 2, 3).

• Bus: Path for data transfer.

  • Bus width and speed affect bandwidth and throughput.

Main Memory

• RAM (Random Access Memory): Main memory for active processes.

  • Volatile, loses data when powered off.

  • Organized as memory modules on the motherboard.

Secondary Storage Systems

• Can be internal, external, or remote.

• Nonvolatile for permanent storage.

• Storage technologies: magnetic, optical, and electronic.

Hard Drives

• Store majority of programs/data; can be external/internal.

• Types:

  • Magnetic Hard Drives: Use hard disks to represent binary data.

  • Solid-State Drives (SSDs): Use flash memory, no moving parts.

Optical Discs

• Data stored via laser in pits and lands.

• Types: CD, DVD, BD (with varying capacities).

• Can be read-only or rewritable (burning data onto the disc).

Flash Memory Systems

• Chip-based storage, no moving parts; more durable, quieter, and energy-efficient.

• Common forms include flash cards, USB drives, SSDs.

Magnetic Tape Systems

• Used for backups and archiving; sequential access only.