cclist at sydex.com
Mon Apr 28 13:22:58 CDT 2008
> Date: Sun, 27 Apr 2008 15:41:49 -0400
> From: Allison
> I have both in quantity. Generally it's the quirks of the
> "improved part"that are annoying but for simple Async serial IO
> they are identical enough.
It could be that simple polled-mode async I/O works well enough, but
when I was trying to get a bisync package working with the 8251, I
wanted to chew my own arm off. Among the issues (other than the
occasional device "hang") that I had was the lack of double-buffering
and the indeterminate control logic (it was possible to disable the
transmitter in the middle of a character). The 8251A was *much*
better in that respect.
In any case, Dwight has the NEC part which renders the topic moot.
I found at the time that the Signetics 2651 was a far better chip for
most utility purposes than the 8251, having the benefit of an
internal baud-rate generator for async operation.
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