Apple Disk ][ X-Ray

[Grant Stockly]

At 12:17 PM 1/3/2007, you wrote:

>"Joachim Thiemann" wrote:
> >
> >Actually, I've been wondering: What is the effect of x-rays on EPROMS?
>
>I was always told it could flip bits.  But that was older UV erasable
>types.  I'd would be interested to know if that is really true...

Most PROM memory can be erased with x-rays, although with FLASH memory it 
actually damages the memory's ability to be reprogrammed before it erases 
them...  (So the erasure risk isn't important)

I've never tried, but heard of people erasing OTP microcontrollers with x-rays.

The 1702 was originally designed to be erased with x-rays and then annealed 
in an oven.  The temperature required to recondition the EPROM was a risk 
to the device.  So they put a window in it.  That's the birth of the window 
on EPROMs (they didn't have windows in the beginning).

One of our customers did some contract work for an electronics company 
once.  They erased a few thousand EPROMs with their x-ray source.  It was 
much faster and cheaper than UV I guess.  I don't know any of the details 
though...


>(I'm having a flash back to wrapping eproms in tin-foil when flying
>prototype game carts and coin-op games out to the west coast.  probably
>just paranoid, but we did that)

That wouldn't do very much at all.  The x-ray machine at the airport goes 
right through tin foil.  1/8 of lead would have worked wonders.  I once 
checked a 30lb slab of lead as luggage.  The screener wasn't expecting a 
cardboard sleeve the SIZE of a national geographic to be so heavy.
: D