Jeff Liebermann wrote:
Well, there's an easy test. Erase your unspecified EPROM. Verify
that every byte is set to FF with the blank check on your unspecified
model EPROM eraser. Create a bin file where all the bytes are
programmed to "OO". Write the file to the EPROM and compare the bin
file with a read from the EPROM. If they're identical, then the
programmer was able to change every cell and there are no bits stuck
at "1". If there are any bytes NOT set to "00", you have at least one
stuck bit.

Joining this late, I want to mention that the 27C series EPROMS can still
be bought. You can buy them from China for about $2 each including postage
for erased and tested "pulls" and new ones can be had for around $45.

They even come in the small flat packages that are common these days.
(sorry, it's late at night, and I don't remember their name)

I specifically needed 27C256's and 27C512's, last summer, so I bought an
eraser for around $15, a USB programmer for under $50 (including the adaptor
for flat packaged chips) and a bunch of $2 chips.

The eraser was an odd combination of a 230 volt unit with a US 120 volt plug,
and a mechanincal timer with a separate on off switch. I replaced the plug
with one more appropriate for my needs and just leave the timer in the
always on position, using an electronic kitchen timer and the on/off switch.

Geoff.


--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379