The nonvolatile, permanent memory that remains in the computer even when it is turned off is called:

ROM which stands for read only memory is non-volatile - this means i t retains its contents even when the computer is turned off, unlike RAM which is the main memory and is temporary and therefore volatile.

ROM memory is also permanent which means once data has been written onto a ROM chip, it cannot be removed and can only be read typically.

ROM = Read Only Memory