Computer Anatomy and Storage Devices

Anatomy of a Computer

• The main components of a computer are input, processing, data storage, and output.
• The Central Processing Unit (CPU) is responsible for executing instructions.
• Magnetic hard disk drives (HDDs) are used for data storage.
• HDDs work by rotating disks coated with magnetic material.

Magnetic Secondary Storage Devices

• Redundant array of independent/inexpensive disks (RAID) combines multiple hard disks into a single logical unit.
• RAID's main goal is to improve reliability and data availability, except for RAID 0, which focuses on performance.
• RAID 0 distributes data across multiple disks, offering speed but no fault tolerance.
• RAID 1, also known as disk mirroring, duplicates data across two disks, ensuring fault tolerance but requiring double the disk space.
• Other RAID types include RAID 5 and RAID 10.

Optical Secondary Storage Devices

• Optical storage devices use lasers to read and write data.
• Common types include CD-ROM, DVD, and Blu-ray high-definition video disk.

Solid State Secondary Storage Devices

• Solid state storage devices (SSDs) store data in memory chips instead of magnetic or optical media.
• Advantages of SSDs include lower power consumption, faster access speeds, and increased durability due to the absence of moving parts.
• A USB flash drive is a typical example of an SSD.

Enterprise Storage Options

• Attached storage connects directly to a single computer or server, typically used for local file and application storage.
• Network-attached storage (NAS) is a storage device or server connected to a network, offering a good option for small businesses and home users.
• Storage area networks (SANs) are high-performance networks dedicated to storage, used by large organizations requiring high availability and scalability.

Virtual Server

• Virtualization divides a single physical server's resources into logical servers, each acting as a dedicated machine.

Data Center

• A data center is a climate-controlled facility housing computer hardware, providing data and information services.
• Efficient operation requires minimizing energy consumption, particularly for cooling.
• Data centers should be located in areas with milder climates, lower energy rates, and affordable land costs.

Computer Hardware Selection

• Computer hardware should be chosen to meet the organization's evolving needs and support its information systems.

Central Processing Unit (CPU)

• Performs arithmetic and logical operations, including addition, subtraction, multiplication, division, and logical comparisons.
• Decodes instructions and coordinates the operations of other CPU components.
• Consists of three main components:
  • Arithmetic/logic unit (ALU)
  • Control unit
  • Register areas

Memory

• Provides the processor with a working storage area to temporarily hold program instructions and data.

Input/Output (I/O) Devices

• Provide data and instructions to the computer, and receive results from it.
• Includes permanent storage

Instruction Execution

• Four steps:
  • Fetch: Retrieves the instruction from memory.
  • Decode: Interprets the instruction to identify the operation and data to be used.
  • Execute: Performs the requested operation using the ALU.
  • Store: Writes the result of the operation to memory.

Decoding

• Breaks down instructions into two parts: opcode (operation code) and address code.
• Opcodes are basic commands that the processor can execute, such as:
  • ADD: Adds two numbers together.
  • COMPARE: Compares numbers.
  • IN: Inputs information from a device (e.g., keyboard).
  • JUMP: Jumps to a designated memory address.

Magnetic Secondary Storage

• Hard disk drive (HDD): Stores data on rapidly rotating disks coated with magnetic material.
• Redundant array of independent/inexpensive disks (RAID): Combines multiple hard disks into a single logical unit to increase reliability and data availability.

RAID Types

• RAID 0: Spreads data across multiple disks for increased speed but lacks fault tolerance.
• RAID 1: Mirrors data across two disks for fault tolerance but requires double the disk space.
• Other RAID types: RAID 5 and RAID 10.

Optical Secondary Storage

• Uses lasers to read and write data.
• Common types:
  • Compact disc read-only memory (CD-ROM)
  • Digital video disc (DVD)
  • Blu-ray high-definition video disk

Solid State Secondary Storage

• Solid state storage devices (SSD): Store data in memory chips rather than magnetic or optical media.
• Advantages:
  • Require less power and provide faster access than magnetic data storage devices.
  • Have no moving parts, making them less fragile than hard disk drives.
• Example: USB flash drive.

Enterprise Storage Options

• Attached storage: Directly connected to a single computer or server for local storage.
• Network-attached storage (NAS): Directly connected to a network, providing storage for small businesses and home users.
• Storage Area Networks (SAN): High-performance network dedicated to storage, used by large businesses and enterprises.

Output Devices

• Display Screens: Show output from the computer.
• LCD (Liquid Crystal Display) and LED LCD: Use a backlight source.
• OLED (Organic Light Emitting Diode): Each pixel emits (produces) light independently, enabling better contrast and lower power consumption.
• E-Ink displays: Found in e-book readers, known for readability in sunlight, minimal power consumption, and reduced eye strain.
• Printers and Plotters: Printers are categorized as laser and inkjet while plotters are used for design work.

Computer System Types

• General-purpose computers: Desktops, laptops, and servers.
• Special-purpose computers: Used in POS systems, medical imaging devices, aircrafts, automobiles, automotive diagnostic computers, and ATMs.

Thin Clients

• Computing devices that rely on a central server for most of their processing and storage needs.
• Minimal local processing and storage, network dependence, and centralized management.
• Examples: Hospital patient room computers and kiosks.

Servers

• Computers used by many users to perform a specific task or service.
• Types:
  • Web server: Delivers web content.
  • DNS server: Converts human-readable domain names into machine-readable IP addresses.
  • Mail server: Sends, receives, and stores email messages.
  • File server: Stores, manages, and shares files with networked clients.