Introduction to EPROM

Read-Only Memory (ROM) is a kind of semiconductor Memory, which features that it cannot be changed or deleted once data is stored. It is usually used in electronic or computer systems that do not need to change data frequently. The data will not disappear because the power supply is off. For example, early PCs such as Apple II or ibm pc xt/AT boot programs (operating systems) or Firmware in various other microcomputer systems ). Only Solid-state semiconductor memory with data stored in advance can be read. ROM. The data stored in ROM is generally written in advance before it is loaded into the entire machine. The entire machine can only be read during operation, rather than being quickly and conveniently rewritten as in random memory. The data stored in ROM is stable, and the data stored after power-off will not change. Its structure is simple and easy to read, so it is often used to store various fixed programs and data. In addition to a few types of read-only memory (such as character generator), the content of read-only memory varies with users. To facilitate usage and mass production, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), and electroerasable programmable read-only memory (EEPROM) are further developed ). The EPROM can be erased only after a long time of ultraviolet radiation, which is inconvenient to use. The EEPROM manufactured in 1980s overcomes the limitations of the EPROM, but the integration is not high and the price is higher. As a result, a new storage unit structure similar to EPROM flash memory was developed. Because of its high integration, low power consumption, small size, and fast online erasure, it has developed rapidly and may replace the existing hard disk and floppy disk and become the main large-capacity storage media. Most read-only memory is made of metal-oxide-Semiconductor (MOS) Fet. Flash rom: FLASH memory, which is essentially an EEPROM-Electrically Erasable read-only memory. In general, flash rom and EPROM are not allowed to be written, you can add a high voltage to write or erase data. Therefore, maintenance and upgrade are convenient. The program disk for BIOS upgrade is generally provided by the motherboard manufacturer or can be downloaded from the Internet. To prevent system paralysis caused by accidental deletion of flash bios content, General motherboard manufacturers have fixed a small boot block in flash bios) it is used to take over the startup of the system in an emergency.