In magnetic surface memory, a device called a magnetic head is used to form and identify different magnetization states in the magnetic layer. The magnetic head is actually an electromagnet with a core made of soft magnetic material and a read and write coil wound around it.

1. Writing operation: When a pulse current in a certain direction passes through the writing coil, a magnetic flux in a certain direction is generated in the iron core.

When writing information, a pulse current in a certain direction passes through the write coil of the magnetic head, and a magnetic flux in a certain direction is generated in the core of the magnetic head. A strong magnetic field is generated at the gap of the magnetic head to form a closed loop. A small area under the head is magnetized to form a magnetized element (ie, recording unit). If a pulse current in the opposite direction passes through the writing coil of the magnetic head, the magnetized element will be magnetized in the opposite direction, and "0" information will be written. After the write pulse disappears, the magnetized element will maintain its original magnetization state to achieve the purpose of writing and storing information.

2. Read operation: When the magnetic head passes through the magnetized element of the magnet-carrying body, since the magnetic head core is a good magnetic conductive material, the magnetic lines of the magnetized element can easily pass through the magnetic head to form a closed magnetic flux loop. Magnetized elements with different polarities have different directions in the iron core.

When reading information, the magnetic head and the magnetic layer move relative to each other. When a certain magnetized element moves below the magnetic head, the magnetic flux in the magnetic head changes greatly, and an induced electromotive force is generated in the readout coil. e, its polarity is opposite to the polarity of the magnetic flux change, that is, when the magnetic flux Φ changes from small to large, the induced electromotive force e is negative polarity; when the magnetic flux Φ changes from large to small, the induced electromotive force e is positive polarity. After the induced electromotive force in different directions is amplified, detected and shaped, it can be identified whether the read information is "0" or "1", thus completing the reading function.

3. Through electromagnetic conversion, the pulse current in the magnetic head write coil can be used to convert a binary code into different residual magnetization states of the magnet-carrying storage element; conversely, through magnetoelectric conversion, the magnetic head can be used to read Out of the coil, the binary code represented by the different residual magnetism states of the storage element can be converted into an electrical signal for output. This is how magnetic surface memory accesses information.

4. After the storage element on the magnetic layer is magnetized, it can be read multiple times without being destroyed. When this batch of information is not needed, all the information recorded on the magnetic layer can be erased through the magnetic head, which is called writing "0". Usually, one magnetic head is used for writing and reading, so it is called a read-write head. Each read-write head corresponds to an information recording track.