Date   : Thu, 20 Oct 2005 23:33:37 +0100
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re:

David Harper wrote:
> Peter Craven wrote:
> 
>> 2. My Solidisk EPROM burner does not burn EProms? I
>> have been using the correct size EPROMS and correct
>> orientation when I insert them. I have been following
>> the instructions re: when to turn Vcc and Vpp on, etc.
>> The lights do come on! The EPROMs are old though. Am I
>> supposed to pulll off the sticky cover over the EPROM
>> window when I try to burn one? Can you just keep
>> burning over the same EPROM, or do you require a new
>> one every time?
> 
> 
> The "E" in EPROM stands for "Erasable". The idea of them is that if you
 
> want
> to re-program one you first erase it, then you program it with the new 
> data.

Not sure how many erase/write cycles each chip will take - circa 1000 
sticks in my brain for some reason, but I don't know if this drastically 
reduces with age (the average 2732 must be 20 years old now, for a chip 
that probably had an expected lifetime of 15 years or so from new)

> It is easiest (and safest) to erase them using a dedicated EPROM eraser
,
> which will supply the right intensity and wavelength of UV for a timed
> interval. (It takes about 10 minutes.) An eraser would set you back abo
ut
> £50 new

leaving them in natural sunlight does work, but it takes a good few days 
to do so :)

UV solarium type lamps don't work apparently; the wavelength is slightly 
out (I'd pondered that one years ago because proper erasers were 
expensive, whilst little solarium units cropped up in second-hand shops 
for a tenner or so all the time)

> you should be able to get one off eBay for a lot less than
> that, or else get a friendly electronics shop to do it for you.

Yep, or local school / university, assuming that they even teach real 
electronics any more :-)

cheers

Jules