ard at p850ug1.demon.co.uk
Mon Jun 27 16:49:23 CDT 2005
> Intel changed the specifications of the 2708 a couple of times, later docs
> state it does not require programming from address 0.
But did they also change the design of the chip, I wonder. Later 2708s
may be more forgiving as to the programming algorithm they'll accept.
Since Intel were so definite about having to go through all locations in
order n times in the data sheet I have, I would certainly want to do it
that way. Other methods might well damage the chip or lead to poor data
> I have changed individual bits (only from a high to low, to go from low to
> high the entire chip must be erased).
You can change individual bits, sure. The data sheet tells you how to do
You have to go through _all_ the locations. If a locations is to be
unchanged, you program it again with its current contents (a special case
of this is that if you want to leave a location totally unprogrammed
after erasing the chip, you re-write it with 0xFF).
> The later docs still state sequential writing but no longer require starting
> at 0 but I have written non sequentially and can swear by that. I wrote a
> program that verified before writing to speed up programming, this skipped
Oh, it probably worked. But I wouldn't recomend doing it. 2708s are
getting harder to find, so I'd not want to risk damaging one. And I
certainly don't want to have to trace a fault caused by an unreliable bit
in an EPROM. I would follow the manfacturer's instructions...
It reminds me af a friend who programmed 27128s with a single 1ms pulse
per location. It seemed to work. They verified OK. And then a bit later
on he got data-rot....
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