8th Class Computers Science Characteristics of Memory Devices Introduction to Primary Memory

     Introduction to Primary Memory  

 Semiconductors Memory

A material which is neither an insulator nor a conductor but can be chemically altered to be either one or zero, when required, is known as semiconductors memory. In manufacturing the electronic circuit (chips), silicon is the primary building blocks used in it. These silicon chips are an excellent semiconductors, thus used to conduct the processor and ultimately the computer or electronic circuits.  

 Random Access Memory (RAM)

There are two types of storage system of computers. These are primary memory and secondary memory. Primary memory is also called RAM (Random Access Memory) or temporary memory is the main memory of computer that is used to store data temporarily while the secondary memory, such as hard disk provides a means of permanently storing the information. RAM is a temporary memory that provides permission to Read and Write over the memory chip. But ROM allows only read permission. RAM is volatile by nature, which means that it needs continuous flow of electricity to keep its content safe. Otherwise as soon as the power is off, the content in the RAM is lost. There are two types of RAM.  

  They are the following: 

• Dynamic Ram (DRAM)
• Static Ram (SRAM)  

 Dynamic RAM (DRAM)

Is one of the forms of semiconductor RAM. In an integrated circuit Dynamic RAM stores information which contains capacitors. In comparison to static RAM, Dynamic RAM is the most commonly used, though they are slower. In comparison to static RAM, Dynamic RAM holds approximately four times as much data of the same complexity.  

  Static RAM (SRAM)

Is a form of semiconductor memory. SRAM storage is based on the logic circuit known as a flip-flop, which retains the information stored in it as long as there is enough power to run the device. A static RAM chip can store only about one-fourth as much data as a DRAM chip of the same complexity. It does not require refreshing and is usually much faster than DRAM. It is also more expensive. SRAMs are usually reserved for use in caches.  

 Read-Only Memory (ROM)

ROM is a type of memory that stores the instructions, which are necessary for starting up the computer. It cannot be written like RAM because as the name implies they are read only memories. But, now few versions of ROM have been launched that includes multiple enhanced features of reading and writing.  

 The following are the types of ROM: 

• Programmable Read - Only Memory (PROM)
• Erasable Programmable Read - Only Memory (EPROM)
• Electrically Erasable Programmable Read - Only Memory (EPROM)  

 Programmable Read-Only Memory (PROM)

Is a type of ROM chip, which allows you to write. But, it provides write permission on chip only once. The PROM cannot be updated further, if it has been used.  

 Erasable Programmable Read-Only Memory (EPROM)

Is a special type of PROM that provides update permission on a PROM memory chip. Unlike PROM, here you can erase the already programmed chip by exposing it to ultraviolet light.  

 Electrically Erasable Programmable Read-Only Memory (EEPROM)

Is again a special type of PROM like EPROM it also allows you to erase the instruction and reprogram the chip. But, here you can erase the chip by exposing it to an electrical charge.  

  Semiconductor memories are electronic data storage. They are made up of______.

(A) Copper                                                         

(B) Iron

(C) Silicon                                                           

(D) Plastic

(E) None of these  

Answer: (c)

Explanation

Correct Option:

(C) Semiconductor memories are made up of silicon.

Incorrect Option:

Rests of the options are invalid.    

 RAM is a temporary memory that provides permission to Read and Write over the memory chip. Dynamic RAM holds approximately________data of the same complexity.

(A) Four times as much                                

(B) Less

(C) Two times less                                          

(D) Two times as much

(E) None of these  

Answer: (a)

Explanation

Correct Option:

(A) In comparison to static RAM, Dynamic RAM holds approximately four times as much data of the same complexity.

Incorrect Option:

Rests of the options are invalid.    

 ROM is a type of memory that stores the instructions, which are necessary for starting up the computer. Which of the following are types of ROM?

(A) PROM                                                           

(B) EPROM

(C) EEPROM                                                      

(D) All of these

(E) None of these  

Answer: (d)

Explanation

Correct Option:

(D) PROM, EPROM and EEPROM are types of ROM.

Incorrect Option: Rests of the options are invalid.