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.
73,
Mike W1NR
+++++++++++++++++++++++++++++++++++++++++++++++++++
Michael A. McCarthy, W1NR
mailto:wa1uar@eecorp.com
WWW: http://www.eecorp.com/~wa1uar
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