What the difference between prom and eprom?

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Discussion Overview

The discussion centers around the differences between PROM (Programmable Read-Only Memory) and EPROM (Erasable Programmable Read-Only Memory), including their definitions, functionalities, and characteristics. Participants explore various types of memory, including EEPROM, and touch on aspects of data retention and erasure methods.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant notes that PROM is defined by address and data, giving an example of 2^4 x 5.
  • Another participant describes EPROM as an "erasable PROM."
  • It is mentioned that EPROM retains stored data even when power is turned off, contrasting it with RAM, which loses data when power is lost.
  • A participant introduces EEPROM as a type of EPROM that can be electrically erased without the need for UV light.
  • One participant explains that the bit patterns in PROM are fixed at manufacture and cannot be changed, while EPROM allows users to define bit patterns using a programmer.
  • Discussion includes that UVEPROM requires exposure to UV light for erasure, and questions arise about whether the erasure process destroys the data or simply resets it.
  • A participant provides a technical description of how an EPROM cell functions, involving a MOS transistor and the trapping of electric charge.

Areas of Agreement / Disagreement

Participants present multiple viewpoints on the characteristics and functionalities of PROM and EPROM, with no clear consensus reached on the specifics of the erasure process for UVEPROM or the implications of data retention in different memory types.

Contextual Notes

Some assumptions about the definitions and functionalities of memory types may be implicit, and there are unresolved questions regarding the erasure process of UVEPROM and its effects on data integrity.

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what the difference between prom and eprom??

i know that prom is defined by address and data like 2^4 X 5

whats eprom then?
 
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erasable prom
 
eprom holds what ever is stored even when the power is turned off, unlike RAM which can be written but will lose data when it looses power.
 
Then there's EEPROM (electrically erasable programable read only memory).
 
The bit patterns in a PROM are defined at the time of manufacture, in the mask.

The bit patterns cannot be changed or erased.

The bit patterns in an EPROM are defined by the user using an eprom programmer.

A UVEPROM (the one with the quartz lid on the top) is erased by exposure to short wavelength UV light.

The EEPROM is an electrically erasable EPROM, where you don't need the UV to erase data.
 
I never knew UVEPROM was real. I saw it in a si-fi thing where it was used as a fail safe on a AI. Do you know how it works, does it just erase it and set everything to 0 or 1 or is it destroyed in the process?
 
madmike159 said:
I never knew UVEPROM was real. I saw it in a si-fi thing where it was used as a fail safe on a AI. Do you know how it works, does it just erase it and set everything to 0 or 1 or is it destroyed in the process?
An EPROM cell is a MOS (metal-oxide-semiconductor) transistor that can be switched on by trapping an electric charge permanently on its gate electrode. This is done by a PAL programmer. The charge remains for many years and can only be removed by exposing the chip to strong ultraviolet light in a device called an EPROM eraser.
http://en.wikipedia.org/wiki/Programmable_logic_device"
 
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