This is the files mentioned in the book "Ruby Developer's Guide"
in the chapter describing Rockit. They are different version of
a simple parser and interpreter for RDG Basic.

iba.rb   - Interactive rdg BAsic 
bint.rb  - Simple version of the RDG Basic INTerpreter
bint2.rb - More advanced version of the RDG Basic INTerpreter

There are also some example RDG basic files:

your_name.rdb - get input from user and print out a message
sumeven.rdb   - sum even numbers between two user-specified limits