Skip to main content

Primary and Secondary Memory.

 .

Primary Memory

  • Primary memory is the main memory of computer. It is used to store data and instructions during the processing of data. Primary memory is semiconductor memory.
  • Primary memory is of two kinds Random Access Memory (RAM) and Read Only Memory (ROM).
  • RAM is volatile. It stores data when the computer is on. The information stored in RAM gets erased when the computer is turned off. RAM provides temporary storage of data and instructions.
  • ROM is non-volatile memory, but it is a read only memory. The storage in ROM is permanent in nature and is used storing standard processing programs that permanently reside in the computer. ROM comes programmed by the manufacturer.
  • RAM stores data and instructions during the execution of instructions. The data and instructions that require processing are brought into the RAM from the storage devices like hard disk. CPU accesses the data and the instructions from RAM, as it can access it at a fast speed than the storage devices connected to the input and output.
  • The input data that is entered using the input unit is stored in RAM, to be made available during the processing of data. Similarly, the output data generated after processing is stored in RAM before being sent to the output devices. Any intermediate results generated during the processing of program are stored in RAM.
  • RAM provides a limited storage capacity.

Secondary  Memory 

  • The secondary memory stores data and instructions permanently. The information can be stored in secondary memory for a long time, and is generally permanent in nature unless erased by the user. It is a non volatile memory.
  • It provides back-up storage for data and instructions. Hard disk drive, floppy drive and optical disk drives are some examples of storage devices.
  • The data and instructions that are currently not being used by CPU, but may be required later for processing are stored in secondary memory.
  • Secondary memory has a high storage capacity than the primary memory.
  • Secondary memory is also cheaper than the primary memory.
  • It takes longer time to access the data and instructions stored in secondary memory than in primary memory.
  • Magnetic tape drives, disk drives and optical disk drives are different types of storage devise.


Comments

Post a Comment

Popular posts from this blog

Introduction of Computer

.  A computer is an electronic device. It take input and store the data in memory and performing the function to produce accurate result in output device. It is used to type document, send email, play game, browse the web and entertainment.   Characteristics of computer  1 . High speed  Computer is very fast device. It is capable of performing calculation of very large amount of data. The computer has unit of speed in microsecond, nanosecond and even in picosecond. The computer is capable of performing millions of tasks per second. 2. Accuracy  The computer produces highly accurate and reliable result.  It does not make any kind of mistake in calculating. The calculation are 100% error free. The computers perform accurate 'n' number of times. 3. Storage capability A computer has much more storage capability. It can store large amount of data. It can store any type of data such as image, video, text document, audio and many more. 4. Diligence Diligence ...
1 comment
Read more

Introduce Linux, UNIX and Linux distribution.

 . Linux Linux is an open source operating system. The term Linux is actually referred to mean a kernel of Unix like operating system developed by a Finish software architect Linus Torvald. The name Linux is derived from Linus' Unix. Linux was originated from the inspiration of a small Unix like operating system MINIX by A.S Tanenbum. Linux is a complete multiuser, multiprocessing, secure and stable operating system which is also considered as UNIX clone. However no code from the proprietary from AT and T is included in Unix. It has flavor of Unix but is not Unix. UNIX  UNIX is a layered operating system. The innermost layer is the hardware that provides the service for the OS. The operating system, referred to in UNIX as the kernel, interacts directly with the hardware and provides the services to the user program. These user programs don't need to know anything about the hardware. They just need to know how to interact with the kernel and it's up to the kernel to provide ...
Post a Comment
Read more

Open System Interconnect (OSI) Reference Model

 . Open system interconnection (OSI) Model explains how packet travels through various layers to other devices on a network, even if the sender and destination have different types of network media. Layer 1(Physical layer):  Function  To activate, maintain, deactivate the physical connection.  To define voltage and data rates needed for transmission.  To convert the digital bits into electrical signals.  To decide weather the transmission the transmission is simplex, half or full duplex.  Physical layer doesn’t perform the detection and correction of errors. Layer 2 (Datalink layer):  Framing (stream of bits into manageable data units):  The datalink layer divides the stream of bits received from the network layer into frame manageable data units called frames.  Physical addressing (MAC Address):  Data link layer adds a header to header to the frame to define the sender and receiver of the frame. Flow Control (mechanism for overwhel...
Post a Comment
Read more