What is prom?

What is prom?

Programmable read-only memory (English: Programmable read-only memory), abbreviated as PROM or FPROM, is a computer storage memory chip. Each bit is composed of a fuse or antifuse. The status determines the data content.

This kind of memory is used to permanently store programs. It is commonly used in various electronic products that pre-store fixed data or programs, such as electronic game consoles and electronic dictionaries. The difference between PROM and narrow ROM (Mask ROM) is that the former can write data as needed after the IC is manufactured, while the data of the latter needs to be created in the IC when the IC is manufactured.

Introduction to programmable read-only memory

Classification

1. Once-programmable read-only memory (ROM)

Programmable read-only memory only allows writing once, so it is also called "One Time Programmable Read-Only Memory" (One Time Progarmming ROM, OTP-ROM). When the PROM leaves the factory, the stored content is all 1, and the user can write data 0 into some of the units as needed (some PROMs have all data as 0 when they leave the factory, so the user can write 1 into some of the units) , to achieve the purpose of "programming" it.

A typical PROM product is a "bipolar fuse structure". If we want to rewrite certain cells, we can pass a large enough current to these cells and maintain them for a certain period of time. The original fuse It can be fused, thus achieving the effect of rewriting certain bits. Another type of classic PROM is a PROM using a "Schottky diode". When it leaves the factory, the diode is in a reverse cutoff state, and a large current method is used to apply the reverse voltage to the "Schottky diode", causing it to Permanent breakdown is enough.

2. Ultraviolet erasable programmable read-only memory (EPROM)

Can use ultraviolet rays to erase original information and rewrite new information.

3. Electrically erasable programmable read-only memory (E2PROM)

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