What is Computer Memory ?
The computer also has its own memory, which is the part of the computer used to store data and instructions in the computer and retrieve them when needed, in which all the data and programs are stored are done. If this part is not there, then any data given to the computer will be lost immediately. So the importance of this part is clear.
This memory can also be considered as the workplace of the computer, where data and information are kept temporarily. When a task is finished, its memory becomes empty i.e. the memory space becomes free on which the next task can be performed. When the power is turned off, everything is erased from this memory and cannot be recovered. This memory of computer is called main memory.
Memory Adresis
The memory of a computer is divided into millions of small blocks. Therefore, the memory of the computer can also be considered as cells and we can consider the cell as a device, where a letter Each cell or location is associated with a number or level called a memory address or location address.
The unit used to measure the storage capacity of a computer , it is called a byte i.e. each cell can be called a byte.
We can classify memory into two parts
Primary memory and secondary memory. Of these, the primary is considered to be part of the CPU and the secondary memory is outside it in the form of magnetic media (such as hard disk, floppy diskette, tape, etc.). Both types of memory have millions of numbers. ( bytes ), in which all types of data and commands are stored in the form of binary numbers. The larger the size of the primary memory of a computer, the faster it is considered to be faster.
There are two types Memory
- Primary memory
- Secondary 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.
SECONDARY MEMORY
This type of memory is outside the CPU, hence it is also called external or auxiliary memory. Due to the fact that the primary memory of the computer is very expensive and most of the information kept in it gets destroyed when the power is turned off, neither we can expand it as desired nor we can store any information in it permanently. So we have to use secondary memory. Its price is comparatively less and the capacity to store data is very high. It has only one drawback that it takes time to write (ie store) and read (ie receive) data in these mediums.
That's why we store such information in it which has to be kept safe for a long time and which is not needed continuously. We can increase the secondary memory to any limit as per our requirement. This memory is in the form of some magnetic devices; For example, floppy disk, hard disk, magnetic tape, CD-ROM etc. Secondary memory is used for backup. When we do not need any data urgently, then it can be stored in a magnetic medium; For example, copying on floppy disk or magnetic tape is saved separately. This is often done to free up the hard disk, so that it can be filled with data that is needed and there is no space on the disk. The data stored in the backup device can be backed up or copied to the hard disk again whenever needed. Devices or devices related to secondary memory are also called mass storage media and devices.
TYPES OF SECONDARY SRORAGE DEVICES
- SEQUENTIAL ACCESS DEVICE
- DIRECT ACCESS DEVICE
■ Sequential Access Device :-
In computing, sequential access memory is a class of data storage devices that read stored data in a sequence. This is in contrast to random access memory where data can be accessed in any order. Sequential access devices are usually a form of magnetic storage or optical storage. While sequential access memory is read in sequence , arbitrary locations can still be accessed by " seeking " to the requested location . This operation , however , is often relatively inefficient .
Types of Sequential Access storage Device
□ Magnetic Tap
A storage technology that is read and written in a serial term. Magnetic tape is the common sequential access storage device.
Magnetic tape is also called magnetic tape. These are considered very safe and cheap means of backing up old files. Magnetic tape is a plastic tape half inch or 12.7 mm wide and hundreds and thousands of feet long, which is wrapped on a spool. On one of its surfaces is a thin layer of a magnetic material.The data is written on this layer by making a magnetic mark. Magnetic tape is very slow, as it is a sequential medium. This means that the work of writing or reading data is done sequentially from one end to the other. We cannot start writing/reading from the middle. The work of reading and writing data on the magnetic tape is done by the tape drive. Its capacity ranges from 40 megabytes to 100 megabytes.
■ Direct Access Device
A direct - access storage device ( DASD ) is another name for secondary storage devices that store data in discrete locations with a unique address , such as hard disk drives , optical drives and most magnetic storage devices . It is a technology and term coined for storage devices that IBM developed for use with mainframe computers and some microcomputers. These developed into the modern hard disk and its variants like the optical disk, which today we would simply secondary storage.
Types of Direct Access Device
Magnetic Disk
Optical Disk
Memory Storage Device
□ Magnetic Disk
A magnetic disk is a storage device that uses a magnetization process to write, rewrite and access data. It is covered with a magnetic coating and stores data in the form of tracks, spots and sectors.
Types of Magnetic Disk
Floppy Disk
Hard Disk
* Floppy Disk
👉 Full details of Floppy Disk
* Hard Disk
The Hard Disk is secondary storage
device. The " hard disk is made of several
circular metal disk coated with magnetic
ink . They are also called as magnetic
disks . Each tracks is divided into different
sectors , which are further divided into
bytes . The time taken to reach to the
specified position is called as latency
time.
Hard Disk are also known as fixed disks.
It is available in many sizes and
capacities. Modern hard disks have
capacity of up to
1000 gigabytes. There are also special
types of hard disks available for personal
computers called Wichester disks. Their
capacity ranges from 20 gigabytes to 80
gigabytes. Hard disk is a very reliable
means of storing information permanently
and the speed of using them is also
sufficient. But they are very sensitive to
dust etc., due to which they are kept
permanently in a box and mounted inside
the system unit.
A block with a typical capacity of 512 bytes
is a section of a track within the sector
limit. Each block has its own read/write
head and sector address. The read/write
head floats above the disk surface and does
not come into contact with it, and therefore
the hard disk remains usable for a long
time. In small computers, such as PCs, the
size of the hard disk is very small.
Types of Head in Hard Disk Drive
The head in a hard disk drive can be
divided into the following two major parts
1. Fixed Head
2. Movable Head
Types of Hard Disk
2. PATA(Parallel Advanced Technology Attachment )
4. SSD (Solid State Drive)
👉 More details of Hard Disk and explain types of Hard Disk .
OPTICAL DISK
Originally developed in the late 1960s , the
first optical disc , created by " James T.
Russell " , stored data as micron - wide
dots of light and dark . Russell's optical
storage system used a powerful backlight
to read the dots through a transparent
sheet of material on which the dots were
encoded. In later optical disc systems, a
laser read the dots and the data was
converted to an electrical signal. Then the
data was converted to audio or visual
TYPES OF OPTICAL DISK
- CD(Compact Disk)
- DVD(Digital Versatile Disc)
- BRD(Blu Ray Disk)
- HVD
■ CD (Compact Disk)
Compact Disk is a special type of disc, on
which data is usually written only once
and then it can be read any number of
times. Laser (Light Amplification by
Stimulated Emission of Radiation)
technology is used to write and read data
on them. Hence they are also called optical
discs. It is a disc made of plastic, on which there is an aluminum plate on both sides.
A thin layer is covered the storage capacity
of a CD ranges from 680 megabytes
to 800 megabytes, it is often read at
a speed of 1200 kilobits per second.
These are called CD-ROM drives. There are
also compact discs available these days
that can read and write data like a normal
floppy, but require a CD-writer. Compact
discs are used only, because all types of
programs are available on these days.
It can be mainly divided into three parts
1. CD ROM (Read Only Memory)
2. CD-R (recordable)
3. CD-RW (re-writable)
👉 Types of CD
■ DVD(Digital Versatile Disc)
DVD stands for Digital Versatile Disc . A
DVD is a type of option media used for
storing digital data. It is the same size as
a CD , but has a larger storage capacity
Some DVDs are formatted specifically for
video playback , while others may contain
different types of data , such as software
programs and computer les The original .
DVD - Video format were developed in
1995. DVDs can be watched repeatedly
without reducing the quality of the video .
A standard video DVD can store 4.7 GB of
data which is enough to hold over 2 hours
of video . Some variations of DVD have
greater capacities .
A dual - layer DVD , which has two layers
of data on a single side of the disc , can
store 8.5 GB of data .
A dual - sided DVD can store 9.4 GB of data
. A dual - layer , dual - sided DVD can store
17.1GB of data DVDs are also used to
distribute software programs. Since some
applications and other software (such as
clip art collections) are too large to fit on a
single 700 MB CD, DVDs provide a way to
distribute large programs on a single disc.
way to store a large number of files and
back up data.
There are four types of DVD
DVD RAM (Random Access Memory)
DVD ROM(Read Only Memory)
DVD R(Recordable)
DVD RW(Re-Writable)
□ DVD- RAM :- DVD-RAM (Random Access Memory) can record and erase data multiple times.
□ DVD -ROM :- Data in DVD-ROM (Read Only Memory) can only be read, not written.
□ DVD-R :- DVD-R (Recordable) can record data only once and then act as a DVD-ROM.
□ DVD RW :- DVD-RW (Re-Writable) can record and erase data multiple time.
■ BRD(BLU - RAY DISK)
Blu - ray is an optical disc format similar
to CD and DVD . It was developed for
recording and playing back high -
definition ( HD ) video and for storing
large amounts of data .
A single Blu - ray disc can hold up to 25 GB
of data . Even a double sided , dual layer
DVD can only hold 17 GB of data . Dual -
layer Blu - ray discs can store up to 50 GB
of data . That is equivalent to 4 hours of
HDTV .
Blu - ray discs can hold more
information than other optical media
because of the blue lasers . The blue -
violet laser has a shorter wavelength
than the red lasers used for CDs and
DVDs.
This allora me laser to focus on a smaller
area ,which makes it possible to store more
data on a dise the same seas a CD or DVD.
■ HVD (Hosted Virtual Desktop)
A hosted virtual desktop ( HVD ) is a user interface that connects to applications and data that are stored on a cloud provider's servers rather than on the user's computer or the corporate network. An HVD is sometimes referred to as a cloud - hosted virtual desktop .
HVD is an optical disc technology developed between April 2004 and mid - 2008 that can store up to several terabytes of data on an optical disc 10 cm or 12 cm in diameter . The company responsible for HVD went bankrupt in 2010 , and the product was not launched .
Memory Storage Device
It is divide into two parts
1. USB Flash Drive (Pendrive)
2. Memory Card (Memory Stick)
1. USB (USB FLASH DRIVE )
A USB flash drive may also be known as a flash drive or USB drive. A USB flash drive is a device used to store data, Most USB flash drives are removable and rewritable. Physically, they are small, durable and reliable. The larger their storage space, the faster they operate. They derive the power to operate from the device to which they are connected (typically a computer) via the USB port. Compared to opuca disk drives, USB flash drives can store more data and also transfer it at a faster rate. It is mainly used to transfer audio, video and data files from the hard drive of a computer to another computer. A USB flash drive consists of a USB connector, which is well protected and electrically insulated inside a plastic or rubber case. A small printed circuit board with surface-mounted integrated circuits are found within the device's casing. The main components of the USB flash drive are:
Standard USB plug-This connects the flash drive to a device.
USB mass storage controller- This is a microcontroller for the USB. It has a small amount of RAM and ROM.
Flash memory chip—The data is stored in this.
Crystal oscillator-the data output is controlled by this component.
2. Memory Card (Memory Stick)
A memory stick is a type of memory card.
This is a USB based memory. Its size is 50.0
x 21.5 x 2.8 mm. Its storage capacity
ranges from 4 megabytes to 256 gigabytes.
Read More :
What is ROM (Read Only Memory) ? & Types of ROM.
Output device and his types define and
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