DEC RRD40 CDROM Drives

From: Clint Wolff <vaxman_at_qwest.net>
Date: Tue Apr 24 19:12:13 2001

On Tue, 24 Apr 2001, Eric Dittman wrote:

> > > Maintaining original labels is going to be hard to do,
> > > as the EPROMs age. I've already had to refresh some
> > > EPROMs from equipment as recent as 1982.
> >
> > Unless your programmer insists on doing a blank-check before programming,
> > you can often refresh EPROMs without erasing them. And thus the label can
> > stay in place. You can often refresh OTP devices in the same way.
> >
> > After all, bit-rot is caused by the charge on the floating gate leaking
> > away. Charge that was put there when the device was programmed. So it can
> > be put back by reprogramming _without erasing first_.
>
> I've actually had an EPROM that would not take the new
> programming until I erased it, and the programmer did
> not require the device to be blank first.
>

An intelligent (modern) programmer will only burn the location until it
reads back correctly. This is done to avoid stressing the cells and
allows more erase cycles. What probably happened is the programmer wrote
it once, read the location was good, and moved on. For some facinating
reading, look at the programming algorithms for an EPROM some day....

clint
Received on Tue Apr 24 2001 - 19:12:13 BST