First part of this Tutorial explains the purpose of program libraries and how to use them. Second part deals with the creation of libraries according to your own needs.
QuickBASIC has a very handy command called CALL INTERRUPT which allows you to perform all the BIOS calls you could ever want. This guide is a brief introduction on how to use BIOS calls including some examples.
Error Table containing all QBasic Error Codes and its corresponding Messages. Useful with ON ERROR ... RESUME Statements.
This is a nice little routine to add menus to your projects.
The 'QBasic Mini Encyclopedia' is an interesting collection with over 20 articles for advanced users and several sample codes. All tutorials are packed in a QBasic program and can be displayed easily by menus.
Another introduction on how to create libraries. This three-part tutorial is available as QBasic source code.
Accessing the command line arguments.
How to put a delay into programs, independent of the CPU speed.