Background Part III – Current Plans

Flash forward to a couple of months ago during a house remodeling project, I came across the old notes of my BASIC and a book that I was taking inspiration from at the time called Writing Interactive Compilers and Interpreters, 1980 by P. J. Brown. I started reading the book and was fascinated. I remembered my BASIC, the promise of the incremental compiler QuickBasic 4.5, and now had a renewed interest in trying to create an interactive incremental BASIC compiler as I had some new ideas – things that I personally have not seen in a development environment during all my years of software development.

My intention this time around is to develop an Interactive BASIC Compiler with an end goal of what I thought QuickBasic should have been. This is going to be a complicated project, so starting small and doing it in stages with several steps each will be required. The initial goal is to get something working and then building upon it. I will not be using anything previously developed from my BASIC interpreter. That was in 6809 assembler and while I do have source listing printouts (any e-copies are long lost), it's not really applicable to the current project. I will be looking at some of the notes I made about the BASIC language itself that I was thinking about at the time as it may be applicable. I will also be looking at existing BASIC compilers for inspiration (FreeBasic, xBasic, RealBasic, TrueBasic, PowerBasic, thinBasic, Smallbasic and of course GW-Basic). This project will not be written in assembly language - that just more effort that I want to take on. The ground rules for now are as follows:

1. Implement a small subset of BASIC commands to start.
2. Implement a selection of immediate commands.
3. Develop on Windows using C++.
4. Use console mode for now (like a BASIC interpreter).
5. Release the code at each stage/step under GPL on SourceForge.

For an interactive compiler to be successful, each line of code must be compiled into a form that is fast to execute (unlike my interpreter), but also needs to be easily able to be converted back into the original source file in the interactive environment. However, the source output may not look identical to what is entered (for example spacing). A large part of the initial effort will be in the design of the internal language and the language parser.

Why even bother as there are so many good software development tools around?  Because the whole idea fascinates me and programming is not only my career, but also a hobby. And maybe I can demonstrate some unique ideas along the way. And I'm really attempting to compete with those other BASICs – that is just not the current goal.