At 10:42 3/09/99 -0400, you wrote:



>The A, B, ... revisions are primarily die shrinks. Some of the errata are
>corrected on newer silicon but sometimes new bugs creep in. Smaller die can
>cause differences in capabilities due to the smaller geometries being less
>forgiving of things like over stressing. On some of the new die the
>programming algorithm has changed and there have been some changes in
>configuration fuses to enhance code protect or to add other features like
>the power up timer. Always use the proper include files and programmer
>selections to be sure of no extra surprise.

The above concurs mostly with what I believe to be true. The A,B revisions
are functional replacements for earlier parts, cheaper and eventually will
replace the older part altogether if not already.

On some later revisions brown out was added and the polarity of the PWRTE
bit reversed in the config word. This is why there are different .INC files
but .INC files are (should be!) the same between all 16Cxx A and B revisions
(and even some non A, B parts (16C63,66,67,72,76,77) too) so that doesn't
quite
answer your question.

The programming algorithm have not changed for A,B revisions but programmer
software may trip up on the different config word settings so it is best
to select the right device if in doubt though I use mixed devices with the
same programmer settings all day.

If you want to know which EPROM parts have the reversed PWRTE, Boden and
better code protection, check out my guide to devices with uneraseable
code protection on my web page under the "knowledge base" link. Substantually
the parts with uneraseable code protection have the reversed PWRTE and
usually brownout too (not 16C92x though.)

Jim


>At 07:03 AM 6/25/99 -0700, you wrote:
>>OK, so I've looked carefully at the data sheets and I STILL can't
>>determine the functional differences between the various flavors of 16C65
>>chips (16C65, 16C65A, 16C65B), except that the plain 16C65 doesn't have a
>>brownout reset capability. Obviously, the A and B chips are different
>>silicon (I have windowed versions of both, and the B die is much smaller)
>>and I know there are some different errata, but are they otherwise
>>identical? If so, why are there different include files in MPASM? (In
>>fact, I just ran a diffs on them, and the A and B files  are identical
>>except for the header info.
>>
>>So I'm still curious: if it was just a silicon rev, why have separate
>>data sheets, etc? Seems overly confusing to me: jeez, I spent a good
>>couple hours just poring through data sheets trying to find the
>>differences.
>>
>>In any case, it seems that as long as I pay attention to the errata, I
>>can freely interchange the A and B versions in my programmer and circuit
>>without any trouble, yes?
>>
>>Dave Johnson
>>
>>
>Larry G. Nelson Sr.
>mailto:L.Nelson@ieee.org
>http://www.ultranet.com/~nr
>
Regards,

Jim Robertson
NEWFOUND ELECTRONICS
________________________________________
Email: newfound@pipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.
________________________________________