Magnetic recorders are the type of analog recorders in which the data is recorded on a thin magnetic tape or wire. A magnetic recorder records the signals of high frequency and reproduces the recorded data in electrical form. The data that is recorded through magnetic recorder can be replayed or reproduced any number of times whenever required.
Figure (1): Magnetic Disk Structure
Magnetic disks are mainly classified into following types.
Mangetic Disk Recorders
Mangetic disk recorders are one of the type of magnetic recorder consisting of a disc coated with a magnetic material. It is used as storage device to store bulk of data for long term in a system (see Figure 1).
The disc that is coated with a magnetic material is made up of one or more flat and circular plates with diameter ranging from 1.8 to 5.25 inches. Each platter is covered with a magnetic material on both the surfaces. The data is stored on the surface in magnetic form either on magnetized or demagnetized layer. In order to carry out read operation, the data present on the magnetized surface is converted into electrical impulses and then send for execution. Whereas, the write operation can be carried out by converting the electrical impulses into magnetic spots.
Hard Disk
Hard disk is the primary storage unit of the computer system. It stores large amount of data and is also known as Data Center. It consists of stack of disc platters made up of alluminium alloy that has a magnetic coating. It holds the data ranging from several hundreds of megabytes to several gigabytes.
Floppy Disk
Floppy disk is a secondary storage device consisting of a disc coated with a magnetic material. The disc with diameter 25 to 50 cm made up of circular, flat mylar plastic acts as a base and support for coating. It is coated on both the sides in such a way that it forms 100 to 1000 tracks. In order to select the required track, the read and write heads are positioned on movable arms. The storage capacity of floppy disk is much higher than other recorders.