Computer Architecture: Hardware, Software, and Components

Posted on Oct 8, 2024 in Computers

Computer Architecture

Hardware and Software

Hardware: The physical devices that make up a computer.

Software: A set of instructions that directs the computer’s components to perform tasks.

Basic Architecture

  • CPU (Central Processing Unit): Processes data.
  • Memory: Stores information being processed and the results (ROM and RAM).
  • Motherboard: The platform where components connect directly or through expansion slots.
  • Peripheral Input/Output: Allows data exchange with external devices.
  • Storage Devices: Permanently store information.

These devices are interconnected and exchange information through buses, which are sets of metal lines. Computer architecture (8, 16, 32, 64-bit) refers to the bus width, or the number of bits transferred simultaneously.

CPU (Microprocessor)

The microprocessor, or CPU, is the computer’s core. It’s an integrated circuit on a silicon chip containing millions of transistors. The CPU processes information received from the user and sends the results to the designated destination.

  • Control Unit (CU): Receives and executes user instructions, managing the ALU and other components.
  • Arithmetic Logic Unit (ALU): Performs mathematical operations (addition, multiplication, division, etc.) as directed by the CU.

The CU and ALU are connected by the bus.

Chipset

Located on the motherboard, the chipset manages external peripherals (through communication ports and expansion slots) and controls data transfer between the CPU and memory. It also determines the CPU model (Intel, AMD, Cyrix, etc.).

Clock

The clock indicates the rate at which the computer performs basic operations. It’s measured in hertz (cycles per second) and synchronizes all devices.

Memory and Storage Devices

These devices retain digital data for a specific time interval.

Memory Types

  • RAM (Random Access Memory): Holds instructions and data for the CPU to process and temporarily stores the results.
  • ROM (Read-Only Memory): Contains firmware (software linked to specific hardware) and is not easily modified. The BIOS ROM contains essential startup instructions and hardware information. Modern BIOS is typically EEPROM (Electrically Erasable and Programmable Read Only Memory).
  • Cache Memory: High-speed RAM. L1 cache is internal to the CPU, while L2 cache is external on the motherboard.
  • Virtual Memory (SWAP): Extends RAM capacity by using disk space. Overuse can lead to system instability.

RAM Technology

Current RAM technology uses a timing signal synchronized with the memory bus clock (currently reaching speeds like 1333 MHz).

  • SDRAM (Single Data Rate Synchronous Dynamic RAM): Used in older systems like Pentium II/III and AMD K6/K7.
  • DDR SDRAM (Double Data Rate SDRAM): Sends data twice per clock cycle.
  • DDR2 SDRAM: Improved DDR, allowing four transfers per clock cycle.
  • DDR3 SDRAM: Offers performance improvements at lower voltage.
  • RDRAM (Rambus DRAM): Proprietary high-end memory used in some servers and the PlayStation 3.

Expansion Cards

Add functionality to the computer (VGA, sound, modem, network, etc.). Sockets include ISA (older), PCI (faster), AGP (for video cards), and variations like PCIX and PCI-Express.

Communication Ports and Connectors

  • Internal Connectors: Connect internal devices (HDD, DVD, fans, power supply).
  • External Connectors/Ports: Connect external devices (PS/2, serial, parallel, USB, Firewire, IR, etc.).

USB (Universal Serial Bus): Supports up to 127 devices and hot-swapping. Versions include USB 1.0 (1.5 Mbps), USB 1.1 (12 Mbps), and USB 2.0 (480 Mbps).

FireWire (IEEE 1394): Similar to USB 2.0, often used for video transfer (480 Mbps).

Infrared (IrDA): Wireless connection, often used in handheld devices.

Storage Devices

Storage devices can be magnetic, optical, magneto-optical, or flash-based.

  • Magnetic Disks (HDD, floppy disks): Store data using magnetic polarization. HDDs are non-volatile, while floppy disks are now largely obsolete.
  • Optical Drives (CD-ROM, DVD-ROM, HD DVD, Blu-ray): Use lasers to read and write data on discs.
  • Magneto-Optical Disks: Combine magnetic and optical technologies.
  • Flash Memory: Uses memory cells (transistors) to store data.

Output Devices (Monitors)

Display processed information.

  • Pixel: Smallest unit on a monitor, composed of red, green, and blue subpixels.
  • Dot Pitch: Distance between pixels. Smaller dot pitch means sharper images.
  • Resolution: Maximum number of pixels displayed.
  • Screen Size: Diagonal measurement of the screen.
  • Bandwidth: Maximum frequency the monitor can handle.
  • Refresh Rate (Hz): Frequency at which the image is refreshed.
  • Monitor Types: CRT, LCD, Plasma, TFT, OLED.

Each color (RGB) is encoded with a byte (8 bits), with intensity measured from 0 to 255. CRT monitors use electron beams, LCDs use liquid crystals, plasma displays use gas, TFTs use transistors, and OLEDs use organic compounds that emit light.