[CQ-Contest] [Fwd: Re: Any CT DOS Experts out there]

David Pruett k8cc at comcast.net
Wed Jun 13 19:42:55 EDT 2007

-------- Original Message --------
Subject: 	Re: [CQ-Contest] Any CT DOS Experts out there
Date: 	Wed, 13 Jun 2007 19:42:27 -0400
From: 	David Pruett <k8cc at comcast.net>
To: 	N6KI Dennis Vernacchia <n6ki_73 at sbcglobal.net>
References: 	<466FB553.3060204 at sbcglobal.net>


I have yet to see a PCI dual COM port card be able to use both ports to 
DOS programs such as CT or NA.  I suspect that this is an IRQ issue.  
Most of these cards have a single IRQ shared between both ports, but CT 
(actually its COMTSR driver) and NA are both designed to have separate 
IRQs for each port.  This cannot be solved in the COMTSR setup; its a 
function of the hardware design, and hence the driver as well (which 
does the low level work to make a PCI card look somewhat like an ISA 
card to the DOS-based program).

I've never had any issues getting DOS software to interface with a PCI 
card with a single COM port and the DOS driver.  I have a pair of old 
Acer Pentium 200 desktops with a built in COM1, a COM2 hooked to a 
hidden modem interface (which I cannot seem to locate on the 
motherboard), and a single-COM PCI card as COM3.  COM1 goes to the 
serial port network, and COM3 to the radio.  Works FB with both CT-DOS 
and NA.

One observation (which might not apply to your situation, but is related 
to the topic) is a problem using IRQ2.  On the PC motherboard, there are 
one or two IRQ controller chips, each of which control up to 8 different 
IRQs.  Very old PCs (pre-286) only had one chip, and so could only 
handle IRQ0 thru IRQ7.  IRQ0 and IRQ1 are used by the operating system 
itself, while IRQ6 is used by the floppy drive.  With the advent of 
80286 and later PCs, a second IRQ controller chip was added, giving 
eight additional IRQs; IRQ8 thru IRQ15.  According to the documentation 
I have, IRQ8 is the clock/calendar, IRQ13 is the math co-processor and 
IRQ14 is the fixed disk drive.

The problem comes that the output of the second IRQ controller is 
daisy-chained to the first controller through IRQ2.  Without boring 
anyone more than necessary, when an IRQ8-IRQ15 occurs, the 2nd chip 
signals the first through IRQ2 which causes the 1st chip to signal the 
CPU, and somehow the operating system figures out which IRQ really occurred.

The reason I bring this up is that I've had ISA COM cards which I've set 
the dip switches for IRQ2, which could work in one computer, but not in 
another (both being 80386 or better machines) with my application 
program (CT or NA) set for IRQ2.  When IRQ2 in the software doesn't 
work, setting the software for IRQ9 (but the card for IRQ2) usually 
works.  This appears to be related to how the BIOS maps the IRQs from 
the 2nd chip, and apparently not all BIOSes work the same.

I apologize if I've bored anyone with all of this IRQ junk...



N6KI Dennis Vernacchia wrote:
> I did post this Query on CT Reflector but thought
> I'd cover my bases in case someone here knows answer
> I have a Celeron machine running DOS/WIN98SE
> I am trying to get CT Ver 10.003 set up for a ham friend
> Problem is it only has 1 COM port on Mother Board
> and I need 2, 1 for Telnet Packet ands 1 for Radio Control
> ( Using Printer Port to key rig for CW - that works fine )
> I managed to find a NEW 2 COM Port ( 2 DB-9s connectors)
> PCI board which I installed and the floppy disk that came with it
> had drivers for DOS and also WIN98
> I did check the company's web site for any new drivers
> and the DOS and WIN98 drivers were the same as on the diskette
> Machine is set to boot into Straight DOS without
> loading any Windows Driver
> ( set GUI=0 in System.ini file )
> That works fine, it boots into DOS on turn on
> I installed the card and DOS driver and I am able to
> do a port test with a DOS Utility and both COM ports
> checkout fine.
> In the CT Directory I load
> COMTSR1 ( For my Telnet Packet input and that works fine )
> I am trying to do radio control for a
> Kenwood TS-950 on one of the new ports on the
> Plug in serial card
> I typed
> COMTSRX -A2E8 -B4800
> ( Where X = 2, 3 and 4 com ports.....to no avail)
> Any ideas what I am doing wrong
> The Blue confirmation Window always comes up and verifies that
> I did in fact get the  desired COM port and the port address
> ( The Serial card booklet instructed me that port addresses
> are 2E8 and 3E8
> ( N81 for other defaults as usual )
> I also went into WIN 98 and loaded those drivers just to be sure
> WIN98 sees the ports and all is well there but I know not
> to run CT for DOS in WIN98
> I do NOT want to run CTWIN if I can help it as have
> had too many problems in the past with Video chipsets etc
> not working correct with CTWIN )
> Ant DOS gurus out there with some other solutions ?
> 73, Dennis N6KI
> Sandy Eggo
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