Date   : Thu, 20 Oct 2005 23:10:11 +0100
From   : "David Harper" <dl.harper@...>
Subject: Re:

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.
The EPROM burner only performs the second of these tasks - you cannot burn
it without erasing it first.

To erase one you have to shine UV light on it. (The sticky cover is to
prevent it being accidentally erased by exposure to sunlight, etc.)

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 about
£50 new, but 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.

David Harper