[ct-user] CT, Com Ports, IRQ's and headaches

Michael A. McCarthy, W1NR Michael A. McCarthy, W1NR" <wa1uar@eecorp.com
Sat, 29 Mar 1997 19:23:45 -0500

You cannot share IRQ's on a PC with standard ISA bus COM cards.  The
card must be capable of using unique IRQ's for each one.  There is
a card available from Comp-USA that has two COM ports configurable
for "Hi-IRQ's".  I use one of these in addition to the two standard
ports for 4 total useable ports.  The software must be capable of
using "non-standard" IRQ's.  Windows can and so can CT but many of
the DOS based logging programs can only use COM1 or 2.  Also, unless
you have a PS-2 type mouse on IRQ 12, a serial mouse must be on COM1
or 2.

Another possibility is a "Digiport" 4 or 8 port COM card which has a
special driver to allow 4 or 8 serial ports on a single IRQ.  Again,
Windows and CT can use them, but most DOS based app's cannot.

> I'm trying to get CT set up using 4 com ports (2 are new).  I never had 
> any problems running with just 2, but more computer control stuff euqals 
> more com ports.  Base addresses are standard, and com 1&3 are IRQ 4 (I 
> think) and com 2&4 are IRQ 3 (at any rate, the com ports share irq's).  
> The comtsr programs are set up to show the proper IRQ's and base 
> addresses, but when I try to use the two com ports that share an IRQ, 
> neither device works properly.  Do I need to configure for individual 
> IRQ's?  The software interrupts on the comtsr programs are all different 
> for the 4 com ports.  
> Thoughts? suggestions?  I'm going to be putting together a 486 over the 
> summer, and will start off right with an 8 port board!  Thanks.
Mike W1NR

Michael A. McCarthy, W1NR
WWW:       http://www.eecorp.com/~wa1uar

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