What is Cache memory?Differentiate between primary and secondary memory

Subject Introduction to Computer System
NU Year Set: 4.(a) Marks: 6 Year: 2010

Cache memory, also called CPU memory, is high-speed static random access memory (SRAM) that a computer microprocessor can access more quickly than it can access regular random access memory (RAM). This memory is typically integrated directly into the CPU chip or placed on a separate chip that has a separate bus interconnect with the CPU. The purpose of cache memory is to store program instructions and data that are used repeatedly in the operation of programs or information that the CPU is likely to need next. The computer processor can access this information quickly from the cache rather than having to get it from computer's main memory. Fast access to these instructions increases the overall speed of the program.

Key Differences Between Primary and Secondary Memory

1.      The key difference between primary and secondary memory is that primary memory can be directly accessed by the CPU whereas, the CPU can not directly access the secondary memory.

2.      The primary memory of the computer is also known as the main memory of the computer. However, secondary memory is known as auxiliary memory.

3.      The data that is to be currently processed is in primary memory whereas, the data that has to be permanently stored is kept in secondary memory.

4.      Primary memory is a volatile memory whereas, the secondary memory is a non-volatile memory.

5.      Primary memories are semiconductor memories whereas; the secondary memories are the magnetic and optical memories.

6.      Data accessing speed of the primary memory is faster than secondary memory.

7.      Primary memory is accessed by the data bus. On the other hand, secondary memory is accessed using input-output channels.

8.      Primary memory’s  capacity is always smaller than secondary memory’s capacity.

9.      Primary memory is costlier than secondary memory.

10.  Primary memory is an internal memory whereas, secondary memory is an external memory.

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