2011年5月24日星期二

System Unit

RAM

Random-access memory (RAM) is a form of computer data storage. It takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. RAM is often associated with volatile types of memory such as DRAM memory modules, where its stored information is lost if the power is removed.

Cache memory

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations. As long as most memory accesses are cached memory locations, the average latency of memory accesses will be closer to the cache latency than to the latency of main memory.

ROM

Read-only memory (ROM) is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware In its strictest sense. ROM refers only to mask ROM ,the oldest type of solid state ROM, which is fabricated with the desired data permanently stored in it, and thus can never be modified.

Flash memory

Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It is primarily used in memory cards, USB flash drives, MP3 players and solid-state drives for general storage and transfer of data between computers and other digital products. Besides, flash memory offers fast read access times and better kinetic shock resistance than hard disks. These characteristics explain the popularity of flash memory in portable devices. The other feature is that when packaged in a "memory card," it is extremely durable, being able to withstand intense pressure, extremes of temperature, and even immersion in water.

Graphic card

A graphics card is an expansion card whose function is to generate output images to a display. Most video cards offer added functions, such as accelerated rendering of 3D scenes and 2D graphics, video capture, TV-tuner adapter, MPEG-2/MPEG-4 decoding, FireWire, light pen, TV output, or the ability to connect multiple monitors. Other modern high performance video cards are used for more graphically demanding purposes, such as PC games.

Sound card

A sound card,also known as an audio card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware inside the PC. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education and entertainment like games and video projection.

Network Interface Card

Often abbreviated as NIC, an expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.

Plug and Play

In computing, plug and play is a term used to describe the characteristic of a computer bus, or device specification, which facilitates the discovery of a hardware component in a system, without the need for physical device configuration, or user intervention in resolving resource conflicts.Plug and play refers to both the boot-time assignment of device resources, and to hotplug systems such as USB and Firewire.

Serial port

In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time. Throughout most of the history of personal computers, data transfer through serial ports connected the computer to devices such as terminals and various peripherals.Server computers may use a serial port as a control console for diagnostics.

Parallel Port

A parallel port is a type of interface found on computers the personal and otherwise for connecting various peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port. The IEEE 1284 standard defines the bi-directional version of the port, which allows the transmission and reception of data bits at the same time.

Universal Serial Bus Port

A universal serial bus port is the gateway to our computer. It's used to connect all kinds of external devices, such as external hard drives, printers, mice, scanners and more. There are normally two half-inch long USB ports on the back of computers built since 1998. Sometimes there are USB ports built into a hatch on the front of a computer.

Firewife port

Firewire ports are forms of a serial port that make use of FireWire technology to transfer data rapidly from one electronic device to another.However, the FireWire port is not just for establishing a connection between various electronic devices and a computer system. In fact, FireWire connections can be created directly between two independent devices.

Ethernet port

An Ethernet port is an opening on computer network equipment that Ethernet cables plug into. These ports are alternatively called jacks or sockets. Ethernet ports accept cables with RJ-45 connectors.Most computers include one built-in Ethernet port for connecting the device to a wired network. A computer's Ethernet port is connected to its internal Ethernet network adapter.

High Definition Multimedia Interface

High-Definition Multimedia Interface also know as HDMI is a compact audio or video interface for transmitting uncompressed digital data. It is a digital alternative to consumer analog standards, such as radio frequency,RF coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, or VGA. HDMI connects digital audio/video sources, video game consoles such as the to compatible digital audio devices, computer monitors, video projectors, and digital televisions.HDMI supports, on a single cable, any uncompressed TV or PC video format, including standard, enhanced and high-definition video.