# Specific 3D Printers, Scanners, & Hardware > RepRap Format Printer Forum > Firmware Enhancements to Marlin >  Jargon bustin'

## old man emu

For the sake of a dumb ol' emu, would you bust some jargon for me?

What's EEPROM?

What programming language is all this bed leveling stuff written in?

Thanks

Old Man Emu

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## Roxy

EEPROM is an acronym for Electrically Erasable Programmable Read Only Memory.    It seems strange it is erasable if it is read only.   But I think they are talking about normal usage.  Most of the access cycles are reads.   When you write something to a location, it has to be erased first and that is a very very slow process.

Marlin firmware is mostly written in .C but the file extensions are C++.   There is some very limited usage of C++ but it would be safe to say it is written in C.    They post processing script we are going to use for scanning through the GCode to limit the probe area is written in Python.   But I don't think you are talking about that.

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## Mjolinor

It developed thus:

PROM: programmable read only memory.
Someone discovered that you could erase it with UV light so they started leaving a clear window in the top (quartz) so we get:
UV EPROM: Ultra violet erasable programmable read only memory. Usually just called EPROM.
Time passes and they developed a way of storing the information permanently but making the chip able to be erased electrically, to distinguish it from a UV EPROM it became known as:
EEPROM: As above.

It is quite common now to leave off the first E as UV EPROMs are rarely used other than in historical equipment.

EEPROM is often also written at E^2PROM or E2PROM or E squared PROM.

You also get MPROM which means mask programmed. That is used for commercial production runs where the manufacturer will programme at manufacture with a fixed data set, non modifiable and non erasable.

There are other obscure things but life's too short.

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## printbus

Oh man.  Thinking back to all that time spent waiting 20-30 minutes for chips to erase in the UV light, and arguing with people at work on who got to use the UV eraser next.

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## Mjolinor

I still have loads of UV roms and a UV eraser. I use them for counters where the count is needing to be an obscure set of bytes.

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## TopJimmyCooks

You still see UV eproms used in 80's and 90's solid state pinball machines.  I don't have an eraser or a programmer, I just order the eproms from vendors who do when I need them.

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## old man emu

*!!!!!! BREAKING NEWS !!!!!!

*Reports are coming in of a massive explosion in a southwest suburb of Sydney, Australia. 

Eye-witnesses report fragments of emu skull raining down from the sky.

One witness, Kevin, told your reported, "I heard that Microsoft start-up music coming from Old Man Emu's computer, then a few minutes later there was a blood-curdling squawk that sounded like EEEEEEEbomb followed by a God-almighty explosion. Guess he read something that blew his mind."

​More information as it comes to hand ...

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