It is a large memory which is fast but not as fast as an internal processor register. The processor directly accesses this memory. It is mainly based on integrated circuit.
The primary memory or the main memory is part of the main computer system. The processor or the CPU directly stores and retrieves information from it. This memory is accessed by the CPU, in a random fashion. That means any location of this memory can be accessed by the CPU to either read information from it, or store information in it. The primary memory itself is implemented by two types of memory technologies. The first is called Random Access Memory (RAM) and the other is Read Only Memory (ROM). A more appropriate name for RAM is RWM (read write memory), the CPU can write and read information from any primary memory location implemented using RAM. The other part of primary memory is implemented using ROM which stands for Read Only Memory.
