Topic 5- selection And Use Of storage Flashcards
Primary storage
Programs and data are stored on chips inside the computer and are available Immediately by the central processing unit
2 types of primary storage
RAM (random access memory)
ROM (read only memory)
Secondary (or backup storage)
outside the computer.
Short delay while the data is obtained from the secondary storage
5 things secondary or backup storage can include
- Magnetic disk
- Magnetic type
- CD-ROM
- CD-RW
- DVD
RAM(random access memory)
fast temporary memory which loses its contents when the power is turned off
ROM (read only memory)
memory stored on a chip which does not lose data when the power is turned off
Volatile memory
memory which loses data when the power is turned off
Non-volatile memory
Memory stored on a chip which does not lose data when the power is turned off
RAM is…
- held on a computer chip
- volatile memory
- read/write so can be altered by the user
ROM is…
- held on a computer chip
- non-volatile memory
- used to hold instructions on computer
- contents cannot be altered by the user
Why is it important to have a large amount of memory?
- applications can run faster on their own
- more applications able to run at the same time
- able to quickly move between applications
What can be used to measure storage capacity and performance
- storage capacity (how much data can be stored usually measured in mb or gb)
- Storage density (ideally you want as much storage as possible in the least possible space)
- access time (time the storage device takes to access a particular piece of data)
- Transfer rate (once the data has been located it will need to be read and transferred to the computer. This measures the throughput of the data)
- physical size (storage devices need to be as small and light as possible)
- portability (some storage devices used for backup should be removable)
What is the amount of data stored and the instructions the computer can store measured by?
-bytes
1 byte= 8 bits
-A single character (letter,number or symbol on the keyboard) can be stored in one byte
-means that one byte is an extremely small unit of storage
3 ways of measuring storage/memory
- megabytes(mb)
- kilobytes(Kb)
- gigabytes(gb)
Smallest to largest file sizes
- Bits
- bytes
- kilobytes (Kb)
- Megabytes(Mb)
- gigabytes (GB)
- terabytes (Tb)
File size conversions of bits,bytes,kilobytes,gigabytes,megabytes,gigabytes,terabytes
Bits (0-1) Bytes=8 bits Kilobytes = 1024 bytes Megabytes = 1024 kilobytes Gigabytes= 1024 megabytes Terabytes= 1024 Gigabytes
Compression
Storing data in a file format that requires less space.
File compression
Files are often compressed before saving on the storage medium and this enables more files to be stored in the same space
Storage device capacity for CD
700Mb
Storage device capacity for Flash drive
4Gb
Storage device capacity for magnetic hard drive
320Gb
Floppy disks and drives
- flexible plastic disks
- not popular anymore because takes long to transfer the data from them (low data transfer speed)
- low storage capacity (1.44mb)
hard drives
Magnetic hard drives advantages
-Consist of a series of disks with a magnetic coating and a series of read/write heads which put the data onto or record it off each surface
Advantages:
- a very high transfer rate
- a very high storage capacity
Optical drives/disks
- flat circular disks on which data is stored as a series of bumps
- the way the bumps reflect laser beam lights used to reader the data off the disk