A BASIC Interpreter Written in Assembly Using HLA
HLABasic started out as a fun project, just playing around writing a BASIC interpreter in assembly language.
Today, it's a fairly complete "traditional" style BASIC interpreter that offers fairly decent performance. The code is all public domain and source code is available, so you can play around with this interpreter to your heart's content and use it anyway you choose.
HLABasic Programmer's Manual (PDF)
HLABasic Implementer's Guide (PDF)
Download the interpreter and source code (source code requires HLA v1.26 or later)