A personal computer is made up of multiple physical components of computer hardware, upon which can be installed a system software called operating system and a multitude of software applications to perform the operator's desired functions.
Though a PC comes in many different forms, a typical personal computer consists of a case or chassis in a tower shape (desktop), containing components such as a motherboard.
The motherboard is the main component inside the case. It is a large rectangular board with integrated circuitry that connects the rest of the parts of the computer including the CPU, the RAM, the disk drives (CD, DVD, hard disk, or any others) as well as any peripherals connected via the ports or the expansion slots.
Components directly attached to the motherboard include:
- The central processing unit (CPU) performs most of the calculations which enable a computer to function, and is sometimes referred to as the "brain" of the computer. It is usually cooled by a heat sink and fan.
- The chip set mediates communication between the CPU and the other components of the system, including main memory.
- RAM (Random Access Memory) stores resident part of the current running OS (OS core and so on) and all running processes (applications parts, using CPU or input/output (I/O) channels or waiting for CPU or I/O channels).
- The BIOS includes boot firmware and power management. The Basic Input Output System tasks are handled by operating system drivers.
- Internal Buses connect the CPU to various internal components and to expansion cards for graphics and sound.
- The north bridge memory controller, for RAM and PCI Express
- PCI Express, for expansion cards such as graphics and physics processors, and high-end network interfaces
- PCI, for other expansion cards
- SATA, for disk drives
- ATA (superseded by SATA)
- AGP (superseded by PCI Express)
- VLB VESA Local Bus (superseded by AGP)
- ISA (expansion card slot format obsolete in PCs, but still used in industrial computers)
- External Bus Controllers support ports for external peripherals. These ports may be controlled directly by the south bridge I/O controller or based on expansion cards attached to the motherboard through the PCI bus.
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