Grex Hardware Conference

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Grex Hardware Item 2: Remember problems with non-Intel 8251's?
Entered by steve on Wed Jul 31 04:42:12 UTC 1991:

   Back a few years ago, there was a _PC Week_ article that stated that
some 8251's had problems with them, and they were not completely, 100%
compatible with the Intel versions.
   Time has passed, and I think that I am once again being haunted by
this problem.  I have some clones that work just fine except when it
comes to serial I/O.  What I remember in the distant past was something
along the lines of bidirectional I/O having the possibility of screwing
up.
   Thats what I seem to be facing now.  No, I forget who made these
8251's, but I know it isn't Intel.  Can anyone out there help out
with the article?

3 responses total.

#1 of 3 by drw on Wed Jul 31 06:54:59 1991:

Steve, are you sure that you're not talking about 8250s. While the 8251 IS
a UART, most of the UARTs that I have found on XT SIO cards have been 8250s.
Another, faster UART (16450 I believe) is used on the 16-bit machines.

#2 of 3 by steve on Wed Jul 31 23:46:45 1991:

   Hey!  Another reason to not write when you're asleep...  Yes,
it was the 8250, not 8251.

#3 of 3 by fes on Fri Aug 9 15:50:05 1991:

There were 8250-A, 8250-B, and 8250-AN - I have the spec sheets from Intel for
these if you're interested. Most of the AT class machines use 16450Ns. I don't
have the sheet on those. The 8250-AN was supposed to have a potential problem
running on the IBM PC. Mail me if you want copies of the Intel stuff.

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