28 Jun
2005
28 Jun
'05
3:26 p.m.
From: "Randy McLaughlin" <cctalk at
randy482.com>
---snip---
Intel changed the specifications of the 2708 a couple
of times, later docs
state it does not require programming from address 0.
I have changed individual bits (only from a high to low, to go from low to
high the entire chip must be erased).
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
many bytes and I used it to modify previously written EPROM's. The buffer
in RAM was sequentially read but the writing was NOT sequential it would
skip bytes when a write was not needed.
Any byte can have high bits changed to low even if they were previously
programmed.
Hi Randy
I recall the primary reason they wanted one to go through
the entire cycle was that it gave the particular spot
that was programmed a chance to cool down. I'm not sure if this
was actually a real problem or just a suspected problem.
I may have been an electrical issue with space charge as well.
Technically, you could skip locations that didn't need
programming but you should insert a delay equal to the
normal total time before programming the same location
again.
Anyway, that is what I remember.
Dwight