🚀 go-pugleaf

RetroBBS NetNews Server

Inspired by RockSolid Light RIP Retro Guy

Article View: comp.sys.ibm.pc.programmer
Article #1491

8250 Software on an AT

#1491
From: Brian Nickerson
Date: Tue, 06 Mar 1990 18:59
25 lines
1601 bytes
  I have been having been doing some serial port software and ran across some
problems that I hope someone has a solution to.  

  The first one was that I couldn't change my baud rate while in the middle of a
connection.  I tried using int 14h with ah=0.  This seemed to hang the port so
I tried a direct write to the divisor latch.  Hung again.  I know several
communication packages that you can change the baud settings at anytime during
the connection.  Does anyone know why my methods would hang the port ?

The other problem I've had was in detecting rings.  I decided that it might be
safer to monitor the modem status instead of relying on the modem's RING
message.  Again, I used int14h with ah=3.  I was masking off the Delta RI bit. 
The 8250 specs indicate that once the register is read that all the Delta bits
are reset.  This didn't seem to be the case because it stayed set as long as
there was ringing on the line (i.e. Delta RI = RI).  I tried doing a direct
read of the modem status register and it made no difference.

If anyone has experienced similar problems and might be able to help, please
send a reply to my uunet address.
-- 


Brian Nickerson
Please send all replies to: uunet!mitel!spock!brian
Technical Details
Message-ID: <2435@sx200d-1>
Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!spock!brian

Show Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!spock!brian
From: brian@spock (Brian Nickerson)
Newsgroups: comp.sys.ibm.pc.programmer
Subject: 8250 Software on an AT
Message-ID: <2435@sx200d-1>
Date: 6 Mar 90 18:59:55 GMT
Reply-To: brian@spock (Brian Nickerson)
Organization: Mitel. Kanata (Ontario). Canada.
Lines: 25