What is Primary Memory?
Primary Memory
Primary Memory It is also called internal or main memory or semiconductor memory, because it is part of the computer's CPU. It contains millions of bytes). Each byte is a series of consecutive bits. Bit is the smallest unit of information. Bit can be thought of like a switch or bulb. A bulb is either burning or is extinguished. We call these two conditions on or off respectively. Apart from these two, no third position is possible, the bit can also have two positions, which we call on or off. For convenience, we denote these positions as 1 and 0. Similarly, a byte consists of 8 such consecutive bits. The value or meaning of the byte is determined according to the positions of these bits. Memory byte is considered to be the smallest unit. Each byte of memory has a special address. Just as the numbers are lying on the houses in a city, similarly the numbers are considered to be lying on the bytes in the memory. These serial numbers start from zero. These numbers are called addresses of bytes.
The size of the primary memory of a computer is measured in gigabytes. The primary memory for ordinary small computers ranges from 1 gigabyte to 4 gigabytes. The primary memory of large computers can be several gigabytes. In the primary memory, the data and the program (or programs) running at that time are temporarily stored for some time. As soon as they are no longer needed, they can be removed and other data or programs can be placed in that place. The size of the primary memory is limited, but its speed is very fast, so that whenever any data is needed, it can be taken from it immediately.
TYPES OF PRIMARY MEMORY
- RAM (Random Access Memory)
- ROM (Read Only Memory )
This memory is like a chip, which is made of metal oxide semiconductor (MOS). It is called RAM in short.
All the information present in RAM is temporary and as soon as the power supply of the computer is turned off, all the information is destroyed i.e. there is a volatile memory. RAM is used to store data and read the data present in it (in memory) RAM is of two types a) Dynamic RAM It is also called D RAM. The storage cell circuits of the DRAM chip consist of a transistor and a capacitor. D RAM is refreshed frequently, due to which its speed slows down. In this way, the dynamic RAM chip provides the facility of such memory, the information of which is lost when the power is turned off.
Types of RAM are
□ STATIC RAM
□ DYNAMIC RAM
* Static RAM
Static RAM It is also called S RAM. In this data is stored as long as the power supply is turned on. The storage cell circuits in static RAM consist of more than one transistor.
Types of STATIC RAM are
( i ) Non - Volatile S RAM
( ii) Asynchronous S RAM
( iii) Synchronous S RAM
Asynchronous SRAM :- Asynchronous In which Address transition has all control of data in and data out , and it contains the independent of clock frequency.
Synchronous :- Synchornous In which , all control signals , data , and address are linked with the clock signals.
* Dynamic RAM
It is also called D RAM. The storage cell circuits of the DRAM chip consist of a transistor and a capacitor. The same RAM is refreshed frequently, due to which its speed slows down. In this way, the dynamic RAM chip provides the facility of such memory, the information of which is lost when the power is turned off.
Types of D-RAM are
( i ) SD RAM (Synchronous Dynamic RAM)
( ii ) RD RAM ( Rambus Dynamic RAM )
( iii ) DDRSD RAM ( Double Data Rate Synchronous Dynamic RAM )
SD RAM :- SDRAM The full form of SDRAM is Synchronous Dynamic Random Access Memory . It works according to the clock synchronization, and it synchronizes with the bus, which is present in CPU of the system. It is faster than the DRAM .
it can access any element of data within 25 to 10 nano second SDRAM are used in the DIMM ( dual in - line memory module ) along with 168 contacts .
RDRAM :- The full form of RDRAM is Ram bus Dynamic Random Access Memory . As the name implies , developed by Rambuys Inc its operating speed more as compared to the other types of DRAM.
RDRAM was designed by Rambus Inc ; especially for graphic card . Now these days , modern RDRAM has higher data transfer rate to CPU memory bus because it includes several new speedup techniques such as synchronous memory interface system caching enabled DRAM chips and faster signal timing RDRAM consist of 8 or 9 bits width data bus.
DDR SDRAM : -DDR SDRAM stands for "Double Data Rate SDRAM", and it provides the more bandwidth to all users. It is capable to accept the same commands at the once per cycle, and it can transfer double words of data with one clock cycle at a same time. Its clock rates are 133 , 166 and 200 MH.
■ ROM (Read Only Memory )
It is called ROM in short. The data and instructions present in this memory are permanent. Due to which they can only be read, but it is not possible to convert them into data and instructions. Due to the stability of data and instructions, the information filled in this chip is preserved even when the power supply of the computer is turned off, that is, ROM is non-volatile memory.
Types of ROM
□ PROM (Programmable Read Only Memory)
□ EPROM (Erasable Programmable Read Only Memory)
□ EEPROM (Electrical Erasable Programmable Read Only Memory)
□ UVEPROM (Ultra Violet Erasable Programmable Read Only Memory)
* PROM(Programmable Read Only)
It is an abbreviation for PROM or Programmable tend Only Memory. It is a memory in which information is stored permanently with the help of a program. P ROM memory can also be filled by the program only once. Like ROM, it is also permanent and cannot be changed later.
* EPROM(Electrically Programmable Read Only)
It is the abbreviation for Erasable Programmable Read Only Memory. It is a P ROM memory that can be reprogrammed. Its information is kept constant by the electric current kept in the chip itself. The information in an EP ROM can be erased by using ultraviolet rays.
* EEP ROM(Electrically Erasable Programmable Read Only)
It is an abbreviation for Electrically Erasable Programmable Read Only Memory. This is an EP ROM that does not need to be removed from the circuit and sent to the manufacturer for reprogramming. It can be programmed in the computer itself with the help of a special software or program. It usually contains information related to the configuration of the computer.
* UVEPROM (Ultra Violet Erasable Programmable Read Only Memory)
UVEPROM is also another type of ROM. In which data can be read / write by some Ultra Violet and It is called (UVEPROM) to record the information of other data in it.
Read More :
What is ROM (Read Only Memory) ? & Types of ROM.
Output device and his types define and
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