Re: Mouse card --- Can EPROM go Bad?

[supertimer@aol.com (Supertimer)]

Frank Carney <frankc@cyberhighway.net> wrote:

>The EPROM does NOT go bad.  The information written on an EPROM simply
>degrades over time.  After 10 years the data will have degraded by %25.
>PROMs and ROMs use a different technology and are probably going to last
>longer than you or I.  You can fix a degraded EPROM by reading the data
>out and writing it back to the EPROM.  This will refresh the data.  You
>do not have to erase it in between when you do this either.  The data is
>the same so there is no reason to erase the original.

EXCELLENT!  That means it does not matter if they stop making
the relevant EPROM chips in the near future.

>If you want to why an EPROM degraded over time it is because you use UV
>to erase it.  There is a constant amount of UV and other energy hitting
>the chip even if it is covered or sealed.  So,  make backups and if you
>need to reprogram the chips.  However, an EPROM has a 100 cycle
>programming life that should be followed.  That means do not program it
>more than 100 times.

Excellent!  I'd be satisfied with that lifetime rating (that's at least
10x99=990 years assuming the EPROM was only programmed
once)!

>Also, I hate it when people post ignorance.  If you know what you are
>talking about, fine, but if you don't look it up or ask someone.

Thanks for setting us straight.  Do you know approximately
when in the degradation time that this degradation will affect
the performance of the hardware?  I assume a 25% degradation
does not because my hardware from 1989 still works.  When
can I expect to see an effect (crashes, etc.)?

The reason I'm asking is because I'm not quite ready to
shell out for an EPROM burner.  These things are rather
expensive.  I hunted them down because I wanted to
preserve my Apple II hardware, but I discovered that
they were all in the hundreds of dollars, with the cheapest
being $129.

What should I look for in an EPROM burner?  Are they
easy to use?  What is a good source of low cost burners?
Thanks!