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VM Ware on W7 X32 with W95 VM loses VM Parallel port / Application Dongle

Hi there, I have a customer with a legacy application that's running on a old/failing box. The os is like a kind of windows 95 dos shell OS and uses a Parallel Dongle as a hardware lock. I have managed to make a Virtual machine and run it a new  Windows 7 x32 box with a PCIe Parallel port card.

It runs fine for a month or two then suddenly the w95 app cannot find the Parallel LTP1 dongle and will not start.

The LPT1 Parallel is still on the host, so If I go into the host device manager, into the properties, into the port settings and change the interrupt settings (doesn't matter which I choose), then click OK I hear the "ding ding" (the same as if you had just plugged in a USB device) then the Virtual Machine works fine until the host is next powered off.

With all that said, I wonder if there is a way to write a small batch file (or something) to make the interrupt change as mentioned above automatically each time the computer is started or as a task when the virtual machine is run.

Really appreciate any useful advice.
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MXDEWD
Asked:
MXDEWD
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2 Solutions
 
MXDEWDAuthor Commented:
FYI - I found this post that explains my problem exactly (with no clear solution).

http://www.44342.com/Visual-Studio--Net-f969-t6281-p1.htm
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Davis McCarnOwnerCommented:
Your problem is that PCI parallel ports hate to be assigned a port and interrupt while the antique software looks at 378, irq7 and 278, irq5 for the dongle, failing if they are not found.
The workaround (hopefully) is to share the port on the host with a short name then create a BAT file with NET USE LPT1: \\hostname\sharename /persistent:yes<enter>.  As a note, this is the old, tried and true method for getting an MSDOS app to print to a Windoze printer.  You may have to setup a generic/ text only printer on the port for the redirect to work properly.
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MXDEWDAuthor Commented:
Hi Davis, thanks for your explanation, it helps to understand what the problem is. I ended up burning the midnight oil on this last night and cobbled together a solution that works well.

Through manual trail and error, I worked out that by disabling then enabling the LPT1 adaptor in the Device manager after a reboot, the VM worked and could see the parallel Dongle. So, using a command line utility from MS, I was able to set a task to run on startup that does the disable and enable in the background. I'm going to keep testing for a few days but it looks stable.
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MXDEWDAuthor Commented:
I worked out the fix for my self prior to anyone posting  solution. That said, the insight provided by Davis helped with the Big picture.
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