ROM / RAM of computer

Memory is known by two types. ROM (Read Only Memory) which means hardware and software can only read the byte values stored inside rom memory and RAM (Read Access Memory) which means hardware and software can not only read the byte values stored inside ram memory but they can also, temporarily, change the byte values stored inside ram memory.

ROM memory is a microchip on a motherboard (green microchip board), such as a Modem motherboard, that contains the instructions (byte values) needed to make the hardware (Modem) work. This is why ROM memory cannot have its byte values changed. The instructions (byte values) are preprogrammed onto the microchip, so that when you first switch on the computer the instructions (byte values) are always the same.

RAM memory is a microchip that is permanently fitted onto a Card (small motherboard), such as a Graphics Card or Memory Card, or a single removable microchip that you attach to the main motherboard. The main motherboard is the big green microchip board inside the computer (base unit). RAM memory can have its byte values temporarily changed, and read, so that you can change Graphics settings (Graphics Card) or store data (Memory Card) for example. Even though RAM memory is cleared when you switch off or restart the computer, because it is meant as a temporary storage place only, the data inside the memory is normally saved by a program (as a file) beforehand. For example. If you change the Modem (hardware) settings using a modem program it will save your changes as a settings file on the hard drive before the computer is switched off or restarted. When the computer is switched on again the modem uses its default (normal, preprogrammed) settings before looking at, and using, the settings from the saved settings file. The modem uses its default settings first for two reasons. One is so that it knows it is setup correctly (by using its normal, manufacturer's, preprogrammed settings) and two is in case the settings file is corrupt, damaged or missing. If it reads a settings file incorrectly (i.e because it is corrupt) you may get problems with the modem or it may revert back to its default settings.