Primary memory can be split into two types: Read Only Memory (ROM) and Random Access Memory (RAM). Random Access Memory is volatile: if the computer is switched off or loses its power supply, data stored in the RAM will be lost. RAM is a more flexible type of memory as its contents can easily be altered at any time. The term ‘random access’ is given to this form of memory because data can be stored and accessed with equal speed from any location inside the memory. The WITCH has ⅓ Kb primary memory (RAM), made up of 828 Dekatrons in nine separate units, used for data and program storage. A dekatron is a type of valve used for volatile memory.