Difference Between PROM and EPROM
By Andrew Parker - December 29, 2022

PROM, or Programmable Read-Only Memory, is a form of ROM that can only be written once. It is designed to meet the needs of a set of ROMs that may have specific memory content. Its memory is written just once and is programmed electrically by the user at the time of chip creation. The user prepares and inserts the appropriate content file into the storage coder machine. Every programmed association has a fuse that blows when the association isn’t needed.

EPROM (Erasable Programmable Read-Only Memory) is a form of optically read and write ROM. its storage cells must remain in their initial condition to write an associated EPROM. EPROM has a lower storage permanence than PROM because of the EPROM’s susceptibility to radiation and electrical noise. MOS (metal-oxide-semiconductor field-effect) transistors are required to fabricate an EPROM.

Chart Summary
  1. Much older and of more extensive scale and flexibility
A modern version of PROM, using MOS transistors


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The fundamental difference between PROM and EPROM is that PROM can only be programmed once since it can only be written once, but EPROM is erasable and can be reprogrammed. There is also a price distinction between the two. While PROM is affordable, EPROM is likely to be more costly.

When it comes to storage, PROM has long storage durability. The storage durability of EPROM is much less than that of PROM. Furthermore, writing to PROMS is irreversible, implying that its memory is permanent, whereas EPROM procedures can be reversed.


The PROM is wrapped in a plastic cowl for safety, while the EPROM is boxed in with a rock crystal window so UV radiation rays can pass through it.

Furthermore, although PROM is a form of ROM that can only be written, EPROM may be read and written optically.
Finally, it becomes useless if a computation error, mistake, or glitch occurs when writing on PROM. Even if there is a miscalculation, mistake, or glitch during writing on EPROM, it will still be used.