27 Apr
2008
27 Apr
'08
12:41 p.m.
Subject: RE: 8251 troubles
From: "Chuck Guzis" <cclist at sydex.com>
Date: Sun, 27 Apr 2008 11:12:06 -0700
To: cctalk at classiccmp.org
Date: Sun, 27 Apr 2008 08:23:09 -0700
From: dwight elvey <dkelvey at hotmail.com>
I'm going to assume that you have an 8251A, not an 8251. If the
latter, either sell it to a collector or have it bronzed and made
into a tieclasp. There are substantial differences between the -A
and non-A parts, all annoying.
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.
The implication is that since the command
register's write-only, you
have to remember the last command you sent if you want to reset the
error flag. One of the minor annoyances of a few early Intel
peripherals.
Yep, helps to have a table of set up variables.
Anent that last one--make certain that your handshake
lines
(RTS/CTS/DTR) are set to the proper levels--an inactive CTS will
prevent the 8251A from transmitting.
Yep,
Allison