The oral mucosa in the area of crenation is usually of normal color, but there may be erythema (redness) if exposed to a high degree of friction or pressure. Crenated tongue is usually asymptomatic and harmless.
ROM stands for read-only memory. It's used to store the start-up instructions for a computer, also known as the firmware. Most modern computers use flash-based ROM. It is part of the BIOS chip, which is located on the motherboard.
CD-ROM's are pre-processed data stored on a CD that cannot be changed but can be copied in some cases. A good example of what CD-ROM's are used for is software and games where the user can open and run the contents of the CD but cannot modify what is contained on the CD.