Wondering what is physically taking place.

 

Interesting question, you just want to know how good we are, don't you? Well, not being one to disappoint, I can answer this. . .

Within the crystalline structure of an EPROM are 'wells' that consist of a a floating gate. This floating gate when programmed takes on a charge. Think of it as a capacitor that will hold its charge for a long time (decades).

When exposed to either UV or x-rays this charge leaks off. Once the charge is depleted that gate will read as a '1' bit. Hence the FFs read on a blank EPROM.

An EPROM can be erased by sunlight. Although it takes a few weeks to do so. A blacklight will not work. This light needs to be shorter then 4000 Angstroms.

EPROMs when in use should always have the window (quartz) covered by an opaque device when in use. A small piece of electrical tape works wonders. Before erasure any glue, gloppies', or dirt should be cleaned off of the window.

RBob.

 

Damn, that is a good answer. Though I may not know everything you are talking about, that is my problem and have some info to research off of to fill in my missing pieces.

I had heard about the uv stuff and the sun but never heard about the black light and that is why I asked the question. I am always looking for a better use for my black light. So far the best use has been finding pet stains in the carpet.

 

Do I understand this correctly, my florescent black light is really a violet light (over 4000 A) and not an ultraviolet light which is light with a wavelength between 1000 A - 4000 A.

Forgot, I used the black light to find an AC leak once.

 

I made my UV eraser from a $5 battery powered flourescent fixture from Home Depot and a $16 "germicidal" bulb I ordered off the 'net. Built the housing out of scrap material I had laying around. Works fine and only have $25 or so invested in it. I hardly use it now since I switched to 29C256 flash chips.