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(Storage Devices and Number System) (Semiconductor Memory semiconductor…
(Storage Devices and Number System)
Semiconductor Memory
semiconductor device tasked with storing data
Types
Volatile memory
SRAM (Static RAM)
DRAM (Dynamic RAM)
Non Volatile memory
FeRAM (ferro electronic RAM)
Mask ROM
EPROM (uv-EPROM)
EEPROM
Flash
Storage medium
Magnetic storage
Stores data in magnetic form
Affected by magnetic fields
Has high storage capacity
Doesn't use a laser to read/write data
Magnetic storage devices (Hard disk, Floppy disk,magnetic tape and etc.
Optical storage
Stores data optically, uses laser to read/write
not affected by magnetic fields
has less storage than a hard disk
data accessing is high, compared to a floppy disc
optical storage devices are CD-ROM, CD-R,CD-RW, DVD etc.
Primary Memory(main memory
)
used for immediate access of data by the
processor
Most computer systems around the world use primary
memory only for bootstrapping and related purposes
Types
RAM
Store data temporary
volatile
store data randomly
data lost if OP switch off
data remain in 2ndary storage
early used delay-line format
modern use embedded RAM circuitary
Form
Static RAM
most expensive
use bistable latching circuitary to store one bit each
faster than its counterpart
modern machine use SRAM as processor cache register
Dynamic RAM
widely used as primary memory
slower than SRAM
inexpensive- one transistor-one capacitor assembly of memory storage
Type
Cache
RAM
Temporary storage and can be permanent
assist direction to previous data
register: storage instruction and data while being used by processor
: fastest memory devices made up of Flip Flops
: costlier memory device
ROM
store data permanently
access and read only
no alter
Types
EPROM
semiconductor
memory
can be programmed and then erased at a later time.
exposing the silicon to ultraviolet light.
PROM
semiconductor memory
data can written only once and permanent
programmed using PROM programmer
EEPROM
Data can be written to it
can be erased using an electrical voltage.
erase pin on the
chip.
retains the contents of the memory even when the
power is turned off
EEPROM is not as fast as RAM
Secondary memory
use for personal data storage purpose.
not directly accessible by the computer
available on mass storage devices for permanent data storage.
data stored will be retained even when it is not supplied any power.
Types
Flash drive
Data storage device that uses flash memory for storage
light-weight, small in design, easily portable
operate from power supplied by a computer's USB port
data can be erased and re-programmed as per requirement.
Punch device
The essential data storage techniques of the '50s and '60s, punch tapes and punch cards have become pass since the advent of newer data storage formats.
A separate tape machine was used to send and receive these tapes for distance communication purposes.
For computing purposes, stored data on the tapes would be read by the processing unit's inbuilt decoding machine.
Magnetic tape
Magnetic tape as a recording technique was invented in 1928.
The device used for the read-write operations on these tapes is called a tape drive.
magnetic tape drives were huge external devices.
The magnetic tape's storage density and feasibility offered it a ready-made advantage against punched storage techniques.
Optical drive
Compact Disc (CD) eventually went on from being an audio disc to a data storage device.
Data storage isn't forfended, DVDs are mostly used for audio and video recording/ storage/ playback purposes.
Floppy disk
The floppy disk memory technique uses a thin plastic-coated film covered with magnetic
material. It is covered with a protective plastic cover.
Initially developed by IBM as inexpensive microcode feeders in 1967.
floppy disks were made commercially available in 1971 to the public
Hard disk drive
Modern external hard disks can hold up to 2 terabytes of data.
typical desktop hard disk is 3.5 inches in size, while for laptops it is 2.5 inches.
External hard disks typically use the USB plug-and-play mechanism and are very cost-effective.
Hard disks seem to be in for the long haul.