While DOS-based applications are slowly fading away, many computer users still use them. In some cases, the software is proprietary Point-of-Sale software that would be cost prohibitive to redesign; in others, the software is perfectly fine as is, so why bother changing it? After all, if the software can run in Windows and performs as it should, who needs a pretty graphical interface?
However, while you can run many DOS-based applications in Windows, you can’t always print their output. DOS applications generally look for a parallel printer installed on LPT 1 and guess what? Today’s modern printers tend to be either USB printers or wireless. Parallel ports are quickly becoming extinct.
In order to get around this, you can use the Microsoft Loopback Adapter and a simple command to trick your DOS application into printing to your USB printer. Here’s how:
First you must install the Microsoft Loopback Adapter. Don’t worry, this isn’t a piece of hardware that you must buy and install. Rather, it is a virtual network adapter that will act much like a real network card.
To install the Loopback Adapter, you will need to go into the Control Panel and select Add Hardware. When prompted, click Next followed by “Yes, I have already connected the hardware.” Continue by clicking Next again and scrolling down to “Add a new hardware device.”
Now, you will need to select “Install the hardware that I manually select from a list (Advanced)” and then select “Network Adapters.” Find Microsoft in the Manufacturer list and then scroll through the Network Adapter list until you find “Microsoft Loopback Adapter.” Follow the prompts to complete the installation.
Once installed, you will need to configure the Loopback Adapter. Go back into the Control Panel and select Network Connections. Now look for the Loopback Adapter in the list of network connections and right-click it. Choose Properties. Select the TCP/IP item and hit Properties. Under the area that says “Use the following IP address” enter a static IP address such as 192.168.1.1. This will create a subnet address of 255.255.255.0. (Depending on your current settings, you may need to pick the next available IP address) Click OK and exit.
Now, share the printer that you will be printing to and give it a memorable name. Once shared, you will then capture the printer port. Go to the Start button and select Run. Now, type in the following in the Run dialogue box:
NET USE LPT1: \\[IP Address]\Printer /PERSISTENT:YES
Click the OK button and try printing from your DOS application. This should work with most DOS-based applications. If not, you might consider purchasing software that is designed specifically for the task. I did a quick Internet search and found several DOS to USB print utilities available. Here’s are two shareware versions that may help:
http://www.freedownloadscenter.com/Business/Printer_Tools/DOS2USB.html

Printers are popular pains-in-the-neck when it comes to networking. Anytime you have multiple computers and devices attempting to “talk” to one another, chances are great the setup with have issues. This is one area of Windows Vista where Microsoft acknowledges potential compatibility issues. There are a few ways to diagnose connection problems with network printers. Most users should start with normal troubleshooting procedures before attempting more advanced options like altering the Internet Protocol version. As a last resort, try contacting Microsoft support for a Hot Fix.