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
28 Jun
28 Jun
5:10 p.m.
From: "Dwight K. Elvey" <dwight.elvey at amd.com>
Sent: Tuesday, June 28, 2005 5:26 PM
docs
Unless you are writing just a few bytes skipping sections doesn't matter.
If for instance you are modifying all 8 bits of one byte and cycle over it
too much it will destroy the chip. Writing 50 or more bytes where you are
modifying an average of 4 bits per byte would not give a problem. Please
note writing a 1 to a bit does nothing and on average only 1/2 of the bits
are changed from a 1 to a 0.
I've programmed hundreds of 2708's and have had few problems. The few
problems I've had have usually been that the EPROM would not erase to all
1's (bad chips).
I have destroyed a couple of 2708's by trying to modify a single byte too
rapidly but I saw it as a learning experience. Since then I learned it is
possible to program a chip rapidly, safely, and reliably.
Randy
www.s100-manuals.com
From:
"Randy McLaughlin" <cctalk at randy482.com>
---snip---
>Intel changed the specifications of the 2708 a couple of times, later >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
7068
days inactive
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days old
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