Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. The hardware of a computer is infrequently changed, in comparison with software and data, which are "soft" in the sense that they are readily created, modified or erased on the computer. Firmware is a special type of software that rarely, if ever, needs to be changed and so is stored on hardware devices such as read-only memory (ROM) where it is not readily changed (and is, therefore, "firm" rather than just "soft").
Most computer hardware is not seen by normal users. It is in embedded systems in automobiles, microwave ovens, electrocardiograph machines, compact disc players, and other devices. Personal computers, the computer hardware familiar to most people, form only a small minority of computers (about 0.2% of all new computers produced in 2003). See Market statistics.
Typical PC hardware
A typical Personal computer consists of a case or chassis in a tower shape (desktop) and the following parts:
Motherboard
The motherboard is the "heart" of the computer, through which all other components interface.
- Central processing unit (CPU) - Performs most of the calculations which enable a computer to function.
- Computer fan - Used to lower the temperature of the computer; a fan is almost always attached to the CPU, and the computer case will generally have several fans to maintain a constant airflow.
- Random Access Memory (RAM) - Fast-access memory that is cleared when the computer is powered-down. RAM attaches directly to the motherboard, and is used to store programs that are currently running.
- Firmware is loaded from the Read only memory ROM run from the Basic Input-Output System (BIOS) or in newer systems Extensible Firmware Interface (EFI) compliant
- Internal Buses - Connections to various internal components.
Storage controllers
Controllers for hard disk, CD-ROM and other drives like internal Zip and Jaz conventionally for a PC are IDE/ATA; the controllers sit directly on the motherboard (on-board) or on expansion cards, such as a Disk array controller. IDE is usually integrated, unlike SCSI which is found in most servers. The floppy drive interface is a legacy MFM interface which is now slowly dissappering. All these interfaces are gradually being phased out to be replaced by SATA and SAS.
Internal storage
Hardware that keeps data inside the computer for later use and remains persistent even when the computer has no power.
- Hard disk - for medium-term storage of data.
- Solid state drive - similar in use to a hard disk, but using more recent technology.
- Disk array controller - a device to manage several hard disks, for example to achieve performance improvement.
Other peripherals
In addition, hardware can include external components of a computer system. The following are either standard or very common.
