14 Dec
2001
14 Dec
'01
12:04 p.m.
8251 was an OK chip, it had bugs, FYI there are three versions
and each has it's oddities! I have tons of them and use them
but, you do have to be aware of the oddities. The worst ones
are initial programming after reset (buffer clear bug) and the
repeats last character on /cts false if TX shifter is not empty
(8251A). However the 2SIO didn't use it.
NS* did use them as did many others. The worst chip was
the 8250.
Allison
-----Original Message-----
From: Gene Buckle <geneb(a)deltasoft.com>
To: 'classiccmp(a)classiccmp.org' <classiccmp(a)classiccmp.org>
Date: Friday, December 14, 2001 12:29 PM
Subject: RE: MITS 2SIO serial chip?
I always thought the 8251 was a pretty kick-ass chip. I learned a lot
about it since the Royal Alphatronic PC that I've got (somewhere in this
disaster of mine) uses it. I was pleasantly surprised a number of years
ago when I discovered someone had made a BYE insert for it. :)
g.
> > Does anyone know what chip was used for the
MITS serial boards? I
thought
that it was the 6850, but I could be wrong.
Weren't a lot of people using the 8251 back in those days?
I had to play some tricks in getting an interrupt-driver
written for the 8251... this was for the redoubtable
Data General One, a sort cool, sorta nasty laptop...
-dq