Type of external memory

Type Of External Memory

                Hi there, there are 3 type of external memory :

J Magnetic Disk

                e.g.:RAID

J Optical Disk

                e.g.:-CD-ROM

                        -CD-R

                        -CD-RW

                        -DVD

J Magnetic Tape

               

                What Is the different between CD-R and CD-RW?

J CD-R : Files only can be save once and after that it only can be read

JCD-RW: Can be use as flash disk . Which mean files and data can be save and edit.

Access Method

                There are 4 type of access method:

J Sequential

-Start at the beginning and read through in order and access time depends location and previous location

-eg:Tape

J Direct

-Individual block as unit address and access is by jumping to vicinity and access time depends on location and previous location

-eg:Disk

J Random

-Individual address identify location exactly and access time is independent of location and previous location

-eg:RAM

J Associative

-Data is located by a comparison with contest of a portion of the store and access tie is independent of location and previous location

-eg:cache

Performance

                3 component in performance:

J Access Time

J Memory-Cycle time

J Transfer Rate

-Muhammad Izzuddin bin Abdul Alim
-B031210175

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