The permanent memory that comes built into a computer is called read-only memory, or ROM. Read-only memory typically holds the most basic level of software that a computer needs to run.
Read-only memory is independent of the operating system, but it offers the foundation that allows the operating system to start. This type of memory can be updated, but it is difficult to do. Other examples can be found in the firmware that runs a cable modem or in a classic video game cartridge. While updating or changing ROM is possible, this type of memory is not at risk for virus or malware infection.