Parallel Port and Windows XP

We purchased two new Compaq computers which came with Windows XP. We want to use these as equipment controllers for our test equipment, (Data Link Analyzer) which is connected to the parallel port.

Our test software runs OK in the DOS environment, but it fails to see the equipment connected to the parallel port and therefore only runs in Demo mode.

If I boot with and old dos ver 6.x, and run my test program works just fine. So XP is doing something to LPT1! Tried all the emulation options, and tried all the BIOS options...to no avail.

Thanks for your help.

 

It may never work for you.

All NT systems (NT4/2K/XP) are written so no application is allowed to make direct calls to hardware to have the hardware do things. Instead, they run a HAL (Hardware Abstraction Layer) which is basically a program within the operating system that traps all hardware calls, examines them, and if they are considered safe by the HAL, it will make the hardware call.

Sometimes a call is considered unsafe and the hardware never sees it. Sometimes the HAL mis-interprets the call and the wrong instructions are sent.

Especially in DOS and Win3.x days, there were serious limitations on what things the hardware could be made to do with normal instructions to the operating system so clever programmers wrote in tricks to allow their software to do what they wanted. 9X/ME allow a program to try whatever it wants so lots of the older stuff would do fine.

The bad news is, some older programs just can't be made to work. The good news is, your system is protected from some of the old programmer tricks that caused crashes.