* The Rate at which data is written to disc or read from disc is called Data Transfer Rate.
* Root Directory is the main folder of disc. It contains information about all folders on the disc.
Memory Cards
These are the data storage devices in a chip shaped which can store the data in it. They are commonly used in many electronic devices, including digital cameras, mobile phone, laptop, etc.
They are small, re-recordable, easily portable and very light weighted.
Secondary memory devices and their storage method and capacity are as follows:
Memory Devices and their Storage Method
| Secondory Memory Devices | Storage Method | Capacity |
|---|---|---|
| Floppy Disk | Magnetic | 1.2MB |
| Floppy Disk | Magnetic | 1.44MB |
| Floppy Disk | Magnetic | 80KB to 242KB |
| CD-ROM | Optical | 640MB to 680MB |
| DVD-ROM | Optical | 4.7GB to 17GB |
| Pen Drive | Solid State | 1GB to 512GB |
| Magnetic Tape | Magnetic | Up to 1 TB |
Units of Memory Measurements
1 Bit = Binary Digit (0 or 1)
4 Bits = 1 Nibble
8 Bits = 1 Byte
1024 Bytes = 1 KB
1024 KB = 1 MB
1024 MB = 1 GB
1024 GB = 1 TB
1024 TB = 1 PB
1024 PB = 1 EB
1024 EB = 1 ZB
1024 ZB = 1 YB
1024 YB = 1 Bronto Byte
1024 BB = 1 Geop Byte
