RAM
Random-access memory (RAM) is a form of computer data storage . Today , 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 . Strictly speaking , modern types of DRAM are therefore not random access , as data is read in bursts , although the name DRAM or RAM has stuck . However , many types of SRAM , ROM , OTP , and NOR flash are still random access even in a strict sense . 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 . On the other hand , Many other types of non-volatile memory are RAM as well , including most types of ROM and a type of flash memory called NOR-Flash . However , other memory devices , for example , magnetic tapes , dicks can access the storage data in a predetermined order , because mechanical designs only allow this .
Cache Memory
The cache is a small amount of high-speed memory , usually with a memory cycle time comparable to the time required by the CPU to fetch one instruction . The cache is usually filled from main memory when instructions or data are fetched into the CPU . Often the main memory will supply a wider data word to the cache than the CPU requires , to fill the cache more rapidly . The amount of information which is replaces at one time in the cache is called the line size for the cache . This is normally the width of the data bus between the cache memory and the main memory . A wide line size for the cache means that several instruction or data words are loaded into the cache at one time , providing a kind of prefetching for instructions or data . Since the cache is small , the effectiveness of the caches relies on the following properties of most program such as ,
Spatial locality is a most program are highly sequential ; the next instruction usually comes from the next memory location .
After that , data is usually structured and data in these structures normally are stored in contiguous memory locations .
Beside that , short loops are a common program structure , especially for the innermost sets of nested loops . Then , this means that the same small set of instructions is used over and over .
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 such as software that is very closely tied to specific hardware , and unlikely to need frequent updates .
On the other hand , in its strictest sense , ROM refers only to mask ROM like the oldest type of solid state ROM , which is fabricated with the desired data permanently stored in it , and thus can never be modified . Despite the simplicity of mask ROM , economies of scale and field-programmability often make reprogrammable technologies more flexible and inexpensive , so mask ROM is rarely used in new products as of 2007 .
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 . It is a specific type of EEPROM as electrically erasable programmable read-only memory , that is erased and programmed in large blocks ; in early flash the entire chip had to be erased at once . Flash memory costs far less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile , solid statestorage is needed .
Graphic Card
A video card , video adapter , graphics accelerator card , display adapter , or 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 graphic , 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 purposes , such as PC games .
Sound Card
A sound card is 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 such as game and video projection . Many computers have sound capabilities built in , while others require additional expansion cards to provide for audio capability .
| A network interface card , more commonly referred to as a NIC is a device that allows computers to be joined together in a LAN , or local area network. Networked computers communicate with each other using a given protocol or agreed-upon language for transmitting data packets between the different machines , known as nodes . The network interface card acts as the liaison for the machine to both send and receive data on the LAN .  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 throungh which information transfer in or out one bit at a time such as contrast parallel port . Throughout most of the history of personal computers , data transfer through serial ports connected the computer to devices such as terminals and various peripherals . On the other hand , modern computers without serial ports may require serial-to-USB converters to allow compatibility with RS 232 serial devices . Serial ports are still used in applications such as industrial automation systems , scientific instrucment , shop till systems and some industrial and consumer products . Server computers may use a serial port as a control console for diagnostics . Network equipment such as routers and switches , often use serial console for configuration .  Parallel Port A paralle port is a type of interface found on computers as prsonal 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 .  Universal Serial Bus Port Universal Serial Bus (USB) is a specification to establish communication between devices and a host controller as usually a personal computer , which has effectively replaced a variety of earlier interfaces such as serial and parallel ports . USB can connect computer peripherals such as mice , keyboards , digital cameras , printers , personal media players , flash derives . Network Adapters and external hard drives . For many of those devices , USB has become the standard connection method . USB was designed for personal computers , but it hs become commonplace on other devices such as smartphones , PDAs , and video game consoles and as power cord .  FireWire 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 . The FireWire port has been in common use since 1995 , when Apple , Inc . First began to include the port on a number of digital camcorders . Today , the FireWire port is used on a number of other devices .  Ethernet port Ethernet is a family of frame -based computer networking technologies for local area networks (LAN) . It defines a number of wiring and signaling standards for the Physical Layer of the standard networking model as well as a common addressing format and a variety of Medium Access Control procedures at the lower part of the Data Link Layer .  High Definition Multimedia Interface HDMI (High-Definition Multimedia Interface) is a compact audio/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 . After that , HDMI implements the ELA/CEA-861 standards , which define video formats and waveforms , transport of compressed , uncompressed , and LPCM audio , auxiliary data and implementations of the VESA EDID . HDMI supports on a single cable , any uncompressed TV or PC video format .  |
