For businesses still reliant on legacy DOS programs, printing can present a significant hurdle when transitioning to modern hardware. Many of these older programs were designed to print exclusively through parallel ports (LPT), a technology largely phased out in contemporary computers that favor USB connections. This article explores a practical solution to enable printing from DOS applications using modern USB printers, ensuring business continuity without disrupting essential workflows.
Understanding the DOS Printing Challenge
The core issue stems from the fundamental differences in printer connectivity between older DOS-based systems and today’s Windows environments. DOS programs were typically configured to communicate with printers via parallel ports like LPT1. Modern computers, however, predominantly utilize USB ports for peripherals, including printers. Directly connecting a USB printer and expecting a DOS program to recognize it as an LPT1 port simply won’t work without intermediary steps.
Alt: Connecting a modern USB printer to a computer illustrates the common interface for contemporary printing.
Furthermore, the transition from 32-bit to 64-bit operating systems can introduce additional layers of complexity. While compatibility layers exist, directly mapping DOS printing functions to modern USB printer drivers requires a workaround. The goal is to create a bridge that allows the DOS program to “think” it’s printing to a traditional LPT port, while the output is seamlessly routed to a USB-connected printer.
The USB to Parallel Adapter and Driver Considerations
A key component in this solution is a USB to parallel printer adapter. These adapters physically bridge the connection gap, allowing you to plug a parallel printer cable into a USB port on your computer. However, simply plugging in the adapter is not enough. Windows needs to recognize and correctly manage the printer.
Alt: A USB to Parallel Printer Adapter is shown, a device crucial for connecting older printers to modern USB ports.
Often, these adapters are automatically recognized by Windows, but they are not typically configured as traditional LPT ports. Instead, they are recognized as USB printing devices. This is where manual configuration becomes necessary. When adding a printer in Windows, you’ll need to manually select the option to “add a local printer” and then “use an existing port.” Critically, you should choose a “virtual printer port for USB,” such as USB001, rather than any LPT port options.
Driver compatibility is another crucial factor. Older printers, particularly dot matrix models, may not have readily available drivers for modern operating systems like Windows 10 or 11. In such cases, finding a compatible driver is essential. Sometimes, a generic driver from the same manufacturer or a driver from a similar, more widely supported printer series can work. For instance, as highlighted in the original article, an Epson FX Series driver can successfully drive an older Panasonic dot matrix printer in a Windows 8.1 environment. Experimentation and online research, including manufacturer support sites and forums, may be required to identify a suitable driver.
Redirecting Print Output with Network Printer Sharing
Even with the correct adapter and driver, the DOS program will still attempt to print to LPT1. To overcome this, we employ a clever technique: network printer sharing and the net use command. The idea is to share the USB printer connected to the computer and then use the net use command within a batch file to redirect the LPT1 port to this shared printer. This effectively tricks the DOS program into printing to the USB printer.
First, share the printer in Windows printer properties. It’s recommended to use a simple share name without spaces for ease of use in the command line. Ensure that the user account running the DOS program has the necessary permissions to access the shared printer.
Alt: The Windows printer sharing dialog box illustrates how to share a printer for network access, a key step in the DOS printing solution.
Next, modify the batch file used to launch the DOS program. By incorporating the net use command before starting the DOS application, we can dynamically redirect the LPT1 port. The following commands are used:
@echo off
::delete the printer port (if it exists)
net use lpt1 /delete
::add the network printer to lpt1
net use lpt1 \COMPUTERNAMEPRINTERSHARENAME /persistent:yes
::fire up the DOS program
START DOSPROGRAM.exeReplace \COMPUTERNAMEPRINTERSHARENAME with the actual network path to your shared printer, where COMPUTERNAME is the name of the computer the printer is physically connected to, and PRINTERSHARENAME is the share name you assigned to the printer. The /persistent:yes switch ensures the printer connection is persistent across sessions.
This batch file first deletes any existing mapping for LPT1 to avoid conflicts and then establishes a new mapping to the shared USB printer. When the DOS program runs and attempts to print to LPT1, it will now be redirected to the specified USB printer.
Applying the Solution to Different Printer Types
This method is versatile and can be applied to various printer types, including both dot matrix and laser printers. The original article successfully implemented this solution for both a Panasonic dot matrix printer and an HP LaserJet 1100 laser printer, demonstrating its adaptability. The key is to find a compatible driver for your specific printer model and to correctly configure the printer sharing and net use command.
Troubleshooting Common Issues
Encountering errors is a common part of technical troubleshooting. Two frequently encountered system errors when using the net use command for printer redirection are System Error 5 and System Error 66.
System Error 5 (Access Denied): This error typically indicates a permissions issue. Ensure that the user account running the batch file and the DOS program has sufficient permissions to access the shared printer. Verify the security settings of the shared printer and confirm the user is listed with appropriate permissions.
System Error 66 (The network resource type is not correct): This error usually points to a syntax error in the net use command. Double-check the computer name, printer share name, and the overall syntax of the command. Ensure that the backslashes are correctly placed and that there are no typos in the names. Referencing the Microsoft documentation for the net use command can be helpful in resolving syntax-related issues.
Conclusion: Sustaining Legacy Systems with USB Printer Integration
By utilizing USB to parallel adapters, understanding driver compatibility, and employing network printer sharing with the net use command, businesses can effectively bridge the gap between legacy DOS programs and modern USB printers. This solution provides a practical and cost-effective way to maintain essential DOS-based workflows while leveraging contemporary printing technology, ensuring business continuity and minimizing disruption during system upgrades. This approach extends the life of valuable legacy software, allowing organizations to modernize their hardware without abandoning critical applications.
