What is the definition of ROM? You've probably heard the term in reference to computers or CDs. "ROM" is actually an acronym standing for "Read-Only Memory." It applies to permanent, non-volatile memory, and it drives the most basic functions of your computer.
ROM refers to both hardware and software.
On the hardware side, ROM is an actual silicon encoded microchip inside your computer. On the software end, this chip contains important information and data, called ROM BIOS, which is necessary for your computer to boot up. This is why ROM is non-volatile, meaning the data is not lost when the system is powered down. It is not to be confused with a different type of memory called RAM. "RAM" is an acronym meaning "Random Access Memory," which refers to memory where data can be removed and altered, and it may not be preserved when a system is turned off.
Putting the "ROM" in "CD-ROM."
You may have heard of compact discs referred to as CD-ROMs, especially when the technology was new. This was because CDs operated by using Read-Only Memory. Initially, CDs were used to play back information such as music or data, and they lacked the ability to record or rewrite information. Then the technology became available for CDs to be altered. The same happened for ROM. Computers today come with rewritable ROMs.
ROM has evolved into PROM and EPROM.
If the ROM contains important information necessary for the computer to boot up, why would it ever need to be rewritten or changed? Before ROM could be rewritten, important system updates could take place only if the ROM chip itself were removed and upgraded. Today's rewritable ROMs are more flexible. These rewritable ROMs include PROMs (programmable read only-memory), EPROMs (erasable read-only memory) and EEPROMs (electrically erasable read-only memory). These types of ROMs are frequently featured in today's computers and make system updates possible without swapping ROM chips.