DIFFERENT TYPE OF MEMORIES USED IN ANY COMPUTER SYSTEM

CPU REGISTER

1. In computer architecture CPU register are the smallest part of storage.
2. They are the fastest storage memory in any computer.
3. They are at the top in memory hierarchy.
4. They are also called processor register.
5. They are use for processor calculations.

They are of different type .

• DATA Register hold the data of integer, float and character type.
• ADDRESS Register hold the address of instruction and indirectly access  to the main memory.
• GENERAL Purpose Registers hold the both address and data i.e., they are combined Data/Address registers.
• FLOATING Point Registers stores the float type data . 
• CONSTANT Registers stores some constant values like one,zero,pi and etc.

CACHE

1. In computer system cache is an important memory which stores data and access it very fast.
2. It is less faster then CPU resisters but it has more memory space then CPU registers.
3. Cache act as intermediate between main memory (RAM) and secondary memory (hard disk).
4. If data found in cache then it is faster process otherwise it is miss.   
5. The transfer of data from hard derive to cache done with the help of replacement policy.

MAIN MEMORY

• Main Memory is also faster memory of computer system.
• It is also called volatile memory because it lost all data after power off.
• It is RAM(Random Access Memory) in computer system.
• RAM is considered “random access” because you can access any memory cell directly if you know the row and column that intersect at that cell.
• RAM is made in electronic chips made of so called semiconductor material, just like processors and many other types of chips.

There are two basic types of RAM :

1. Dynamic Ram
2. Static Ram

Dynamic RAM : loses its stored information in a very short time  even when power supply is on. D-RAM’s are cheaper & lower.

In the most common form of computer memory, Dynamic Memory Cell, represents a single bit of data. The capacitor holds the bit of information – a 0 or a 1. The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state. A capacitor is like a small bucket that is able to store electrons. To store a 1 in the memory cell, the bucket is filled with electrons.

To store a 0, it is emptied. The problem with the capacitor’s bucket is that it has a leak. In a matter of a few milliseconds a full bucket becomes empty. Therefore, for dynamic memory to work, either the CPU or the Memory Controller has to come along and recharge all of the capacitors holding it before they discharge. To do this, the memory controller reads the memory and then writes it right back. This refresh operation happens automatically thousands of times per second.

This refresh operation is where dynamic RAM gets its name. Dynamic RAM has to be dynamically refreshed all of the time or it forgets what it is holding. The downside of all of this refreshing is that it takes time and slows down the memory.

Static RAM : uses a completely different technology. S-RAM retains stored information only as long as the power supply is on. Static RAM’s are costlier and consume more power. They have higher speed than D-RAMs. They store information in Hip-Hope.

In static RAM, a form of flip-flop holds each bit of memory. A flip-flop for a memory cell takes four or six transistors along with some wiring, but never has to be refreshed. This makes static RAM significantly faster than dynamic RAM. However, because it has more parts, a static memory cell takes up a lot more space on a chip than a dynamic memory cell. Therefore, you get less memory per chip, and that makes static RAM a lot more expensive. Static RAM is fast and expensive, and dynamic RAM is less expensive and slower. Static RAM is used to create the CPU’s speed sensitive cache, while dynamic RAM forms the larger system RAM space.

HARD DERIVE

• HARD DERIVE, also known as auxiliary storage, secondary storage, secondary memory, Auxiliary memory or external memory.
• It is use to store the bulk data.
• It slowest memory in computer system.
• It stores data permanently so that it is called non-volatile memory.
• It made with the help of magnetic component so that it is called Magnetic Disk.
•  It is lest expensive memory in computer system.