Chapter 13

Secondary Storage device

Storage capacity

1TB = 1024 GB;   1GB = 1024 MB;   1MB = 1024KB;   1KB = 1024B

210 =1024

1 Byte = 8 bits

Access time: It is the average time taken for the device to search and read the required data.

Data transfer time: Amount of data can be transferred between main memory and a storage device.

Magnetic storage devices

Direct Access

Floppy disk : 1.44MB

Hard disk: Platter / Cylinder / Track Cluster (refer to P.73-75 of textbook)

Magnetic tapes (Backup) - sequential access

Optical storage device

CD-ROM

DVD

HD DVD

Blu-ray Disc

Other forms of storage devices

Memory cards, USB flash drive

SSD hard disk (no rotation needed, higher access time, no defragmentation needed)

Network storage

13.6 Latest development of secondary storage device