Memory is an internal storage area in the computer used to store data and programs that is temporarily or permanently. Computer memory is divided into two groups
While the primary memory holds instructions and data when the program is executing. To executive a program all the instructions or data that has to be used by the CPU has to be loaded into main memory or primary memory.
However the primary memory is volatile means it can stores our data temporarily and so it can retain only when the power is on moreover it is very expensive and therefore Limited in capacity
Coming to Secondary memory it holds data and programs that are not currently in use and provides long-term storage it will stores data permanently even when the power is turned off it is cheap and can store large volumes of data and we can move it from one computer to another computer.
The only drawback of secondary memory is that data can be accessed from it only at very low speeds as compared to with the data access speed of the primary memory
Examples for secondary memory includes hard disk drives optical disk drives and other devices that are slower than RAM but are used to store data permanently
Catche memory is an extremely fastest type memory and it acts as a intermediate between RAM and CPU.
If you use cache memory to store instructions and data that are repeatedly required to execute programs thereby improving the overall system speed and increasing the performance of the computer
Working of the Cache Memory
When a program is being executed the CPU wants to read data or instructions in the following steps are performed.
The CPU first checks whether the data or instruction is available in the cache memory if it is not present there the CPU reads data and instructions from the main memory into the processor registers and also copies it into cache memory when the same piece of Data is needed again the CPU reads it from the cache memory inside of the main memory
Primary memory or Main memory or internal memory is a type of memory that is directly accessed by the CPU. The CPU continuously read instructions stored in the primary memory and execute them. Any data that has to be operated by the CPU is also stored there and the primary memory is divided into two types RAM and ROM
Random Access Memory
RAM is volatile Storage Area within the computer that is typically used to store data temporarily RAM Full form is Random Access Memory.
RAM is considered Random Access because any memory cell can be directly accessed if its address is known, when the RAM gets full the computer system operates at a slow speed when we are doing multitasking means opening multiple applications and using them it makes RAM fullfully occupied.If we want to make your PC very faster we have to store small data in our RAM
This Memory is Divided into 7 types:
Synchronous Dynamic RAM(SDRAM)
Enhanced Synchronous Dynamic RAM(ESDRAM)
Double Data Rate SDRAM(DDDSDRAM)
Synchronous Link Dynamic RAM(SLDRAM)
Read only Memory
ROM Full form is Read Only Memory(ROM) It is non volatile that is the data is retained in it even after the computer is turned off.Moreover read only memory is used extensively in calculators and peripheral devices such as laser printers whose fonts are often stored in read only memory.
Read only Memory is divided into 3 types:
Programmable Read Only Memory(PROM)
Erasable Programmable Read Only Memory(EPROM)
Electrically Erasable Programmable Read Only Memory(EEPROM)
Secondary storage devices
Secondary storage also known as External Memory differs from primary memory in that it is not directly accessible by the CPU.The secondary storage devices holds the data even when the computer is switched off. An example of such a device is the hard disk.
Storage devices are non-volatile in nature cheaper than primary memory and can be used to store huge amounts of data when the CPU can read the data stored in the main memory in nanoseconds the data from the secondary storage devices can be accessed in milliseconds
The hard disk is a part of the computer that stores all the programs and files if the drive is damaged for some reason all data stored on the computer is lost the hard drive means hard disk for its relatively quick access to large amounts of data stored on a electromagnetically charged surface.Today's pc’s come with a hard disc that can store gigabytes of data
Optical storage refers to storing data on an optically readable medium by making marks in a pattern that can be read using a beam of laser light precisely focused on spinning disc. Optical storage devices are the most widely used under reliable storage devices.
The most popular optical storage devices are CD-ROM , DVD-ROM, CD-RECORDABLE,CD-REWRITABLE etc.
Today every computer contains a CD-ROM driving a single CD can hold a large amount of data including software movies on Fox by some optical storage media is read only others or read and write enabled
USB FLASH DRIVES
USB flash drives are removed rewritable and physically much smaller,weighing less than 30 grams.In 2010 the storage capacity of the USB flash drive was as a lot just 256 GB.These USB devices are good suitable than floppy disk and CD ROM as they are smaller faster have thousands of times more capacity and are more durable and reliable. Till 2005 most desktop and laptop computers had floppy disk drives but nowadays floppy disk drives have been abandoned in favour of USB ports
Floppy disk or storage devices that consists of a thin Magnetic storage medium in Union Square plastic still lined with fabric that removes the dust particles the storage capacity of floppy disk is very limited as compared to Cds and flash drives all the floppy drives are very cheap they are much lower than other data storage device.
Moreover floppy disk must be handled with utmost care as they are vulnerable to damage from Misshandling for example data stored on A floppy disk can be lost if the disc is bended, removed while in use are exposed to excessive temperature,dust of smoke.
Memory is a small device that can store digital files.we can insert memory card into a computer or mobile and we can Store file such as text documents ,pictures, audio files and video files and then remove the card and take it to another computer ,where it can be inserted to copy the file from the local disk of that computer and we can add or delete files multiple time.Memory card have smaller in size and larger in data storage capacity