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What is ROMWhat is ROM - Computer Memory - Computer ROM - Memory - Read Only Memory - Memory Card - RAM - ROM - ROMS - FirmwareROM stands for Read Only Memory. The ROM contains instructions that are permanently stored by the manufacturers when they manufacture the chips. In fact recording data and instructions permanently into this kind of memory is called "burning in the data". The instructions stored in ROM can only be read but cannot be modified. This is the reason why it is called Read Only Memory. ROM is a semiconductor chip programmed at the time of its manufacture and is not re-programmable by the user. The programs stored in ROM are called firmware. It is a non-volatile memory. The contents of ROM are not lost when the computer is turned off. The ROM contains the Basic Input / Output System (BIOS which is a set of instructions that are automatically activated when the computer is turned on. It means that computer uses the instructions of ROM at the time of booting for the following purposes.
Many other devices also contain ROM chips. For example a printer has a ROM chip that contains data or information for fonts. You can say that each electronic device has ROM chip that contains information about that device. The ROM is further divided into:
1. PROM PROM stands for Programmable Read Only Memory. PROM is a blank ROM chip on which the user can write his own program instructions and data but only once. However once the program or data is written in PROM chip, it cannot be changed. The programmer uses micro-code instructions to write information in a PROM chip. Once the programmer writes the micro-code on the PROM chip, it functions like a normal ROM chip. 2. EPROM Once ROM or PROM is programmed, its contents cannot be changed. However there is another type of memory chip called EPROM that overcomes this problem. EPROM stands for Erasable Programmable Read Only Memory. It is another important form of read only memory. Like PROM, it is initially blank and the user or manufacture can writes his own program or data by using special devices. Unlike PROM the data written in EPROM chip can be erased by using special purpose devices and ultraviolet rays. So program or data written in EPROM chip can be changed and new data can also be added on this form of ROM. When EPROM is in use, its contents can only be read. 3. EEPROM EEPROM stands for Electrically Erasable Programmable Read Only Memory. This kind of ROM can be re-written by using electrical devices and so data stored on this ROM chip can be easily modified. See Also or Related Articles:
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