ON THIS PAGE YOU WILL FIND THE DEFINITION OF ROM AND TYPES OF ROM.AS WELL AS CD-ROM,CD-R,CD-RW.THE CD-DA,CD&G,CD-i,CD+MIDI, CD-PLUS,AND THE YELLOW,RED AND GREEN BOOK STANDARDS.

ROM : READ ON MEMORY

Computer memory on which data has been prerecorded.Once data has been written onto a ROM chip,it cannot be removed and can only be read.

Unlike main memory (RAM),ROM retains its contents even when the computer is turned off.ROM is referred to as being nonvolatile,whereas RAM is volatile.

Most personal computers contain a small amount of ROM that stores critical programs such as the program that boots the computer.In addition, ROMs are used extensively in calculators and peripheral devices such as laser printers, whose fonts are often stored in ROMs.

SOME TYPES OF ROM :

EEPROM :

Electrically erasable programmable read-only memory. EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM,EEPROM retains its contents Even when the power is turned off. Also like other types of ROM,EEPROM is not as fast as RAM.EEPROM is similar to flash memory (sometimes called flash EEPROM).The principal difference is that EEPROM requires data tobe written or erased one byte at a time where as flash memory allows data to be written or erased in blocks.This makes flash memory faster.

EPROM :

Erasable programmable read-only memory,EPROM is a special type of memory that retains its contents until it is exposed to ultraviolet light.The ultraviolet light clears its contents,making it possible to reprogram the memory. To write to and erase an EPROM,you need a special device called a PROM programmer or PROM burner.

An EPROM differs from a PROM in that a PROM can be written
to only once and cannot be erased.EPROMs are used widelyin personal computers because they enable the manufacturer to change the contents of the PROM before the computer is actually shipped.This means that bugs can be removedand new versions installed shortly before delivery.

PROM :

Programmable read-only memory.A PROM is a memory chip on which data can be written only once.Once a program has been written onto a PROM,it remains there forever.Unlike RAM,
PROMs retain their contents when the computer is turned off.

The difference between a PROM and a ROM (read-only memory)is that a PROM is manufactured as blank memory,where as a ROM is programmed during the manufacturing process.To write data onto a PROM chip, you need a special device called a PROM programmer or PROM burner.The processof programming a PROM is sometimes called burning the PROM.

EAROM :

Electrically Alterable ROM

EROM :

Erasable ROM

CD ROM

COMPACT DISK/READ-ONLY MEMORY A READ ONLY COMPACT STORAGE DISK FOR AUDIO OR VIDEO DATA.

CDR

COMPACT DISK -RECORDABLE A TYPE OF DISK DRIVE THAT CAN
CREATE CD-ROM`S AND AUDIO CD`S.CAN ONLY BE WRITTEN TO ONCE.

CD RW

COMPACT DISK REWRITEABLE A RECORDABLE CD-ROM THAT MAY
BE WRITTEN OVER MANY TIMES.

THE FOLLOWING TERMS REFER TO SPECIFIC TYPES OF CDs AND CD FORMATS.

CD-DA =

Compact disc-digital audio; the format used for high-fidelity music that offers a 90+ decibel signal-to-noise ratio and 74 minutes of digital sound.The standard for this format is the Red Book.Audio files are uncompressed 16-bit,44.1-kHz samples.

CD+G

Compact disc + graphics; developed by Warner New Media,this CD format is not readable by standard CD-ROM players.It includes extended graphics capabilities,as well as some limited video graphics written to the CD subcode area.The primary use is for karaoke,in which song lyrics are displayed and the musicis Played without vocalsto accompany a person who singsthe song.

CD-i :

Compact disc-interactive audio levels; levels of audio encoding that are part of the Green Book specification. Level A is a method of recording audio that offers fidelity comparable to that of standard CD audio,but it compresses the data to about half as much space on a disc. Level B is used in both the CD-i and CD-ROM XA formats; this method of recording audio offers medium fidelity but is more highly compressed than level A. Used in both the CD-i and CD-ROM XA formats, level C is a method of recording audio that offers fidelity sufficient for speech. It is highly compressed.

CD+MIDI :

Compact disc + Musical Instrument Digital Interface; Developed by Warner New Media,this CD format adds MIDI information to the digital audio data.

CD-plus :

A CD-ROM format from Sony and Philips that plays Red Book audio, written on the first tracks,and that includes graphics and data files readable by a microcomputer on later tracks.Windows 95 supports the CD-plus format.

CD-R :

Compact disc- record able;developed in 1990 by Philips and Sony,it adheres to the Orange Book standard.It permits a CD recorder to write CD-DA,CD-ROM,CD-ROM XA ,and CD-i block structures to a blank CD-ROM disc.The primary applications
are for prototype production discs,or one-offs,and for archiving data.In 1992,a second generation of CD recorders became standard.They are capable of multi session recording,or writing additional information to a disc without deleting existing data.To read a multi session disc,readers must be able to identify a complex table of contents (TOC), but not all reader scan do this. The original ISO 9660 logical file structure does not handle multi session discs,because it was created before their invention.

STANDARDS

Yellow Book Standard :

The specification for standard CD-ROMs.Based on the Red Book audio standard,which preceded it,this standard defines two new modes: mode 1 and mode 2. It also establishes a third layer of error correction.

Red Book Standard :

The audio CD specification that Philips and Sony developed. The specification Book defining the format for audio CDs originally had a red cover. In other books defining CD standards,many parameters are based on those in the Red Book.

Green Book Standard :

The specification for CD-i developed in 1991 by Philips. Discs that adhere to this CD-ROM format contain audio files, digital data, still graphics, and MPEG video. An infrared remote control device, a mouse, or a trackball allows users to interact with the content on the disc by clicking a cursor over hot spots on the video display.