EPROM Memory

EPROMs (Erasable Programmable Read-Only Memories) are non-volatile memories that can be rewritten with a special device. As defective PROMs (earlier non erasable counterparts) were investigated because they seemingly lost memory, the cause was identified and used to invent the EPROM.

In 1971. Intel released the first EPROM for the general public, the 1701, which could store 256 bytes of data.

To rewrite an EPROM, it must first be erased with an ultraviolet light, which is why the the chip package has a quartz window. Then, a programmer is used to write new data. EPROM chips were also used to make PROMs with windowless packages so it was not possible to do the erasure step.

Intel C1702A Intel C4702A Intel B1702A
  • A C1702A EPROM. Bottom. Mexico, 1974 Week 8. On the die, one can read "1602A", which was a PROM model, a good example of what is stated above.
  • A C4702A EPROM. Bottom. Malaysia, 1975 Week 23. The 4702 is just a 1702 renaming for the 4004.
  • A B1702A EPROM. Bottom. Malaysia, 1976 Week 27.