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Read Only Memory

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ROM is a type of memory that can’t be written to as easily as RAM can. It is often used for “firmware”. Firmware is software that’s so essential to the operation of computer hardware that it must be guaranteed to be present and uncorrupted on the hardware for anything to function.

In the ancient days of the PC revolution (i.e. the 1980’s), home computers like the Commodore 64 and the Apple II did not come equipped with disk drives to load an operating system from. Instead, the entire OS was designed to fit onto a small ROM firmware, which was embedded within the computer. When the computer was booted up, the first thing it did was start executing the code on that ROM, which would initialize all the other hardware and then give the user a BASIC interface.

Another type of system that makes good use of Read Only Memory is a video game system like Sega Genesis or Game Boy Advance. These systems stored their games on ROM chips that were embedded in a larger protective cartridge. The cartridge (or cart) had sturdy connectors that let a young person safely plug and unplug the game without risk of damaging the ROM inside.

Some of the more commonly known video game systems that use(d) ROM to distribute their games are:

Atari 2600
Intellivision
Colecovision
Nintendo Entertainment System (NES)
Sega Master System
Sega Genesis
Super Nintendo
Turbo Grafix 16
Neo-Geo
Nintendo 64
Game Boy
Game Boy Color
Game Boy Advance
Nintendo DS

One of the reasons so many video game systems use(d) ROM for distribution is that ROM makes it more difficult for a customer to make illegal copies of the software. In disk-based systems, piracy is usually a matter of just figuring out how to copy a disk with your home PC. When copying (or dumping) a ROM, you must have special hardware for reading the ROM chip and saving its stored data back to a network, disk, or another ROM.

Another reason for using ROM chips for video games is simplicity. Once a ROM is connected to the data bus of a system, it can be read just like RAM. This makes the game developer’s job easier (no need to interface with a disk or tape drive), and it makes the hardware more affordable (no need to include an expensive disk drive with the game system).

Of course, copies of almost all cartridge-based games have been made, either by either pirate hackers or video game enthusiasts. Now, it is often possible to download the data from the old ROMs of these video game systems. The data files are generally also called ROMs. These ROMs can be loaded by emulators that let you play them as if you had the original game system hardware.

Of course, ROMs aren’t all firmware and video games. If you’ve ever installed a program on your PC, you’ve used another type of ROM: the CD-ROM. Another type of ROM is DVD-ROM. In both cases, the Read Only Memory in question is encoded as a series of microscopic pits and grooves etched into a reflective surface.

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