Editing Dartmouth BASIC (section)

===Seventh Edition===
Garland's SBASIC was a pre-compiler written in SBASIC source code itself. The system would read SBASIC source, write the corresponding 6th Edition code, and then compile that output. The Seventh Edition, released in 1980, was a version of SBASIC that was a stand-alone compiler of its own. It added a number of additions of its own. Most of the changes were further elaborations on the system for calling external programs and "overlays" that could be used to break up a program into parts. In this version, <code>SUB</code>s sharing a single file effectively shared data between them. This provided a modicum of [[data hiding]] within the group of routines. This separation would today be known as a module.{{sfn|Elliott|1988|p=135}}

In addition, this edition added structured error handling and arbitrary matrix math in <code>LET</code> statements, so one could <code>LET A = M*4</code> where M was a matrix variable, and the statement would output another matrix into A with all the elements in M scaled by 4. Finally, another major update was the use of [[activation record]]s for subroutines which made [[recursion]] possible.{{sfn|Elliott|1988|p=135}}