Here are two programs which will run under QBASIC - you should find QBASIC.EXE in your DOS directory.

If you suffer from Windows 95, you can load Qbasic onto your system from the W95 options disk.

Save the programs as Bilby5qb.bas and Stepkey.bas respectively - you will probably not be able to run them from within the Netscape or Explorer environments. Run Qbasic and load them in the normal way. Double-clicking on them in File Manager might work instead.

STEPKEY.BAS is a simple demonstrator of how to drive two stepper motors from the printer port of a PC.
If you do not want to connect stepper motors, the screen display is still worth seeing.
When you press a cursor key, you will see two 'compass needlse' rotate to represent the wheels of a Bilby.
At the same time you will see the bit-pattern being output on the printer port.

BILBY5QB.BAS is still only half written. Already, however, it will allow you to design and save a bilby maze. It will also let you see the signals from three sensors so that you can try driving the bilby by hand, using the cursor keys to drive or turn the bilby.

There is also an Auto choice, where the bilby obeys an algorithm which has been put in one of the 'SUB's.
The algorithm here is not very good - deliberately! You will have to edit the program (it really should be clear how) to put in a better algorithm of your own choice - the one you intend to use on your 'real reality' bilby.