yabasi 0.3

Minimal BASIC interpreter for running MININEC

Author:

Ralf Schlatterbeck <[e-mail]>

This is a BASIC interpreter for an old dialect of the language used in early IBM PCs. It is written in Python. I wrote this over a weekend to be able to run old MININEC code (the linked version of MININEC contains some small fixes). It has almost no error checking (it relies on the code being correct not trying to aid you in writing a new program in BASIC, I think the world does not need new code in BASIC). If you’re looking for a working BASIC interpreter, look at the pcbasic implementation, it is also in Python but faithfully reproduces the memory limitations of the machines at the time. And it seems to use single-precision floating point numbers. This is why I wrote my own interpreter: I needed to compare computations in double precision and I could not fit some examples into the limited memory of pcbasic.

I’m probably not going to put much work into improving this code, it has achieved the purpose: Running (and debugging in Python) old MININEC code to allow me to compare the computations in BASIC to my re-implementation of MININEC in Python, pymininec.

Changes

Version 0.3: Fix rules for printlist

The syntax of parameters to the PRINT statement can either use a semicolon (or a comma) to separate expressions or just put the expressions together without a separator. The latter had some quite ad-hoc rules and I’ve removed many of them, the result removes a reduce/reduce conflict…

Version 0.2: First working (released) version