Date   : Sat, 29 Oct 2005 01:03:17 +0200 (BST)
From   : Johan Heuseveldt <johan@...>
Subject: Re: Re[2]:

Hi,

On Thu 20 Oct, Jeff Gaines wrote:
> 
> Hello Group,
> 
> > 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?
> 
> It's been 20+ years since I burnt one but I seem to remember you had
> to expose the window to UV light to erase them.

Yes, correct:

You cannot program '1' bits into an EPROM, only turning '1' bits into
'0' bits. You can only get back '1' bits by exposing the EPROM internals
to UV light, for which a window is available. That obviously needs to be
uncovered to perform UV erasing processs, and after programming needs to
covered again, although not time critical


greetings,
Johan

-- 
Johan Heuseveldt <johan@...              >
  aka  waarland

  The best place is a Riscy place
 
The bag that breaks is the one with the eggs.