This is one of a fewimages I produced using a QBasic image opener. I haven’t yet seen anyone else take advantage of QBasic for glitching, but it produces the kind of errors you could see on the first windows machines 20 years ago. The basic procedure is:
Choose a source image and find a QBasic image opener. Example .bas files can be found everywhere online (I used Yousuf Philips’ 24-bit BMP opener, written in 1998). Almost all of these will use SCREEN 13 to display the file, which means the final result will be 320x200 pixels or less, but these programs will almost always resize the original, so it tends not to be a problem.
Open the .bas file in QBasic and alter various elements of the code. Although it’s best to retain the structure of the file, I found a number of lines that could easily be altered. The best things to look for are the colour palette, and any equations. As SCREEN 13 has 256 colour palette, playing with the colour palette will affect how the colours from the source image are processed. If you want to play with equations, insert a few multipliers, additional variables and random elements.
Run your program. If you’re getting errors, check your syntax, or undo until you get something more sensible.
If you like it, print-screen your output, if not, play around with your modifications until you get something you do like.