DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

Post by tim.mcga » Sun, 13 Feb 2005 06:33:19

I'll preface this message by stating that I am an END-user of software,

without any real intuitive insight into how programming code actually
works. Therefore the following question/problem will, no doubt, betray
my programming naivete.

I use Virtual PC for Mac 7.0 (Windows XP) for a single purpose...... to

operate a very old (but for me, essential) custom software
package.....essentially an antiquated DOS beast.

I used to carry around an old Thinkpad-X20 in my briefcase for the sole

purpose of being able to run this software (everything else I do with a

computer is on my beloved Powerbook).

For the most part, the old DOS-based billing software runs just fine in

Virtual PC on my Powerbook, and I can enter all of my new weekly data
without a problem.

However..... the problem arises when this DOS-based program tries to
find, initialize, and use the internal modem on the Mac. It just can't
do it..... so I have to copy the datafile to my desktop PC once a week
in order to be able to submit my data by modem.

Perhaps one of you can look at what the DOS software is attempting to
do, from within Virtual PC environment in which I am running it, and
advise whether any subtle changes would let it find the Mac internal

The modem.dat file that the DOS program is attempting to use has the
following content/format....


In looking at the preceding..... can anyone offer some insight as to
how this message string might possibly be reconfigured to enable it to:

a) accomplish what it is attempting to accomplish above, but....
b) accomplish this through finding the internal modem on the Powerbook
that is running Virtual PC rather than the Windows-based internal modem

with which it is impotently attempting to communicate?


DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

Post by John McGhi » Sun, 13 Feb 2005 16:58:42

i Tim:

Noooo.... Sorry :-) DOS programs can't communicate with the Internet, and
it would take some very serious computer programming indeed to change that.

The problem is not that it "can't find the modem", but that VPC does not
"have" a modem.

VPC sets up a direct connection to the Mac's Internet connection (it
emulates an Ethernet connection). So it appears to VPC as though it is a
computer in an office with a hard-wired network connection to a server
(which just happens to be the Mac).

What I suggest that you do is this:

1) Enable Shared Networking in Virtual PC (the Help tells you how).

2) Make sure your VPC Additions are up-to-date (the help tells how)

3) Enable Shared Folders in VPC (the Help...)

4) Bring up your network connection using the Mac's modem

5) From inside your PC, save your file out of the DOS program.

6) Using Windows Explorer or My Computer, copy the file to the Mac HD

7) Start off an Email in your Mac email program.

8) Attach the file from your Mac HD to the email and "Send".

You could, if you wanted to, in Step 6 use Outlook Express in the Virtual PC
to send the email directly from the PC without copying it to the Mac hard
disk. This would be simpler, but I prefer not to have two email programs in
different places each handling part of my mail. I'm too old for the
confusion that results and mistakes that get made :-)

Hope this helps

On 12/2/05 8:33 AM, in article


Please reply to the newsgroup to maintain the thread. Please do not email
me unless I ask you to.

John McGhie < XXXX@XXXXX.COM >
Microsoft MVP, Word and Word for Macintosh. Consultant Technical Writer
Sydney, Australia +61 4 1209 1410


DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

Post by Michael Pa » Sun, 13 Feb 2005 17:10:29

OS programs can't communicate with the Internet...
except for Arachne (MS DOS 3.3 or higher!)
But I doubt if it would work under VPC.

Michael Paine

John McGhie [MVP - Word and Word Macintosh] wrote:


DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

Post by tim.mcga » Mon, 14 Feb 2005 01:06:53

Thanks for your detailed response, John.

I'll offer a bit more clarification.

When operating when installed on my old Thinkpad.... this DOS software
was not really trying to "communicate with the internet". Instead, it
was using the dial-up modem on the Thinkpad to connect by long distance
telephone line to the dial-up modem of PC in a firm that incorporates
the received data into their weekly "tape" data submission (on behalf
of my clinic and the numerous other clinics that contract with this
firm) to our provincial health care insurer (the public health care
equivalent, in Canada, of an HMO in the US).

Please help me understand the comment in your second paragraph,
regarding a modem.

For example........if I were travelling with my Powerbook and relying
upon my Earthlink dial-up internet connection (rather than the cable
internet connection at home and work).... what does VPC do if:

i) I am not already in the middle of a dial-up Internet session on my
Powerbook, and;
ii) I launch Internet Explorer from Windows in VPC.

I would naively expect that VPC would only be able to establish the
Internet connection, in the
preceding scenario, by means of initiation of a dial-up connection to
my Earthlink ISP provider and that this, in turn, would involve it's
recognizing or communicating with the internal dial-up modem on my

Not sure if I am making this clear, but I wanted to elaborate... since
my read of your explanation, suggested that you were under the
impressing that this was an e-mail issue or that this involved being
able to use the cable internet connection active on my Powerbook. In
contrast, my issue directly involves being able to use the Powerbook's
dial-up modem for a dial-up connection to a computer in a different

In light of the above clarification.... is there any further advice
that you could offer?




DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

Post by Steve Jai » Mon, 14 Feb 2005 06:17:02

oes your DOS app allow you to modify the COM settings? Does it match
the COM1/COM2 of the modem configured in VPC?

Have you set up the modem/serial port in the VM? Check VPC's help for
info on this.

On 12 Feb 2005 08:06:53 -0800, XXXX@XXXXX.COM wrote:

Steve Jain, Virtual Machine MVP
"This posting is provided "AS IS" with
no warranties, and confers no rights.
You assume all risk for your use."

DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

Post by Unseeli » Wed, 16 Feb 2005 06:49:31

I have yet to see an app that could recognize the modem under Virtual
PC. I assume this is why they recommend setting up the modem manually
in VPC help.

Assign the Mac built in modem to COM1
In Windows, add the modem, configure manually, and use Standard 56000
modem for the description file.

That's not going to help much with a DOS application, however.

Steve is right, it will need to access the modem on COM1 or COM2 or it
will fail. If it uses a specific modem driver/description file, it will
likely fail as the built in Mac modem is likely not compatible with
that driver.

DOS-based software, running in Virtual PC (Windows XP) 7.0 for Mac, can't find Mac modem

Post by H.Tomar » Fri, 18 Feb 2005 02:01:39

In theory, your DOS program should be able to access serial port on the
Virtual Machine if you connect the Mac internal modem to the appropriate
COM port in the Virtual Machine Settings. It may access the hardware
registers directly. And whether the WinXP allows DOS programs to
directly access hardware registers is another problem. Whether your Mac
internal modem is compatible with VPC7 is also unknown.

In my experience , I could use a DOS program to record Closed Caption in
DOS6 on VPC6. It reads CC characters from serial port (Keyspan
Serial-USB Adapter) connected to a Closed Caption decoder. It was not
perfect: it sometimes failed to catch some characters... So I made a
simple recorder on OSX.

If DOS6 runs in VPC7, you can try your DOS program in the operating
system on which it was originally supposed to run. You may want
now-defunct VPC additions for DOS system, which enables you to share
folders with OSX.

You can also try other PC emulators such as Qemu.