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Re: Apple II+ Flakey Inverse Characters

mwillegal wrote:

That part should work in a RFI board, though it is interesting that an
EPROM would fail in a very similar way to a 2513.


From what I can tell, the failure mode doesn't involve any particular
pattern, just random bit flips.  That seems like a plausible failure
mode for both an old mask-programmed ROM and for a floating-gate EPROM.


Regards,
Mike Willegal

On Jan 8, 10:50 pm, wrodiger <wrodi...@gmail.com> wrote:


On Jan 8, 4:20 pm, mwillegal <m...@willegal.net> wrote:







I think that you are on the right track.



A flakey 2513 was my first guess, but you indicated that it only
happened
in inverse mode.  This problem should not be dependant upon mode,
though it
may be more obvious in certain modes. I had a batch of NOS 2513 chips
where
about 50% of them had this issue.



Regards,
Mike Willegal



PS
the 341-0036 character rom part listed on the site you mention is not
a 2513 and is not compatible
with early Apple II motherboards.


My motherboard is a revision 7 RFI board, so I am hoping it matches...
if not, I assume I can locate the binary image and burn my own?

Will


-michael

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