8250 Software on an AT

Thread View: comp.sys.ibm.pc.programmer

1 messages

[T] Back to Threads [V] Tree View [G] Group Articles

1 total messages Started by Brian Nickerson Tue, 06 Mar 1990 18:59

#1491

Author: 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

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads