Since the internal storage capacity of PCs is limited, it places a restriction on how much data can be stored at a time for processing. However, this is not the only drawback. Once the PC is switched off, or in case of a power failure, all the data stored in the internal storage is lost. This means that every time you want to work on the PC, you would have to input the data required for processing.
For permanent storage of data, external storage media can be used with a PC system. External storage is also referred to as secondary storage.
There are two kinds of external storage media used with a PC, they are:
- Floppy Disk
- Hard Disk
Another media for external storage is the cartridge tape. It is particularly suitable for storage of large volumes of data. Now, CD-ROMs and Magneto-Optical (MO) disks have also become an important media to store large volumes of data.
Floppy Disk | Hard Disk |
| Also referred to as diskettes or floppies. | Also referred to as the fixed disk. |
| Removable. Suitable for moving data from one computer to another. | Non-removable. It is attached within the system unit. |
| Made of flexible vinyl material. Less resistant to damage by heat, dust and accidental twists. | Less prone to damage since it is within the system unit and is packed airtight. |
| The diskettes currently in use have a diameter of 3.5 inches with a storage capacity of 720KB or 1.44MB. | Can store data in the range of 20 MB to a few GB. |
| Diskettes having a diameter of 5.25 Inches and a typical storage capacity of 360KB is also used, but is slowly being phased out. |
Comparison between a Diskette and a Hard Disk