8251 troubles

[Chuck Guzis]

> 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. 

Cheers,
Chuck