If everything in RAM is erased when the power is turned off, how does the computer start up again? The answer is read-only memory as you seen on the topic (ROM), a type of memory on which instructions have been prerecorded. The instructions to start the computer are stored in read-only memory chips. ROM only allows these instructions to be read; they cannot be erased. In contrast with RAM, ROM retains information even when the power is switched off.