QBasic

Qbasic has been around for... for... Ever! Ok. Since 1991. It is based off QuickBasic (a basic complier) but without the complier and linker. It only functions as a interpreter so it can't make stand alones (EXEs). It has its' own built in IDE and inline error handling. This will only catch simple typos. For a programing language it is a bit dated, but it is free, easy to understand, and will run on anything! From MS-Dos 3.2 to Windows Vista and Linux. I would recommend running Qbasic through DosBox for XP or Vista.