REAL-TIME BASIC (RTB) for Varian 620 Computers (Oregon/Nebraska Version)

Abstract

The basic programming approach described in this section may be implemented on Varian 620/i, 620/L, and 620/f computers. In addition, the Varian 73 computer can be used in the same way. Our development of real-time basic (rtb) for these systems has relied on simple modifications of the basic compiler as supplied by Varian. This compiler is a version of the language, originally developed at Dartmouth College, which includes all of the standard arithmetic operations as well as trigonometric functions and matrix-algebra routines. The standard Varian version of the language requires approximately seven thousand words of memory for the compiler, leaving the remainder available for user source code. A user may expand the available source-code area (thus allowing larger programs) by deletion of the matrix algebra and/or trigonometric function packages. This yields about 700 additional words of memory. Since this is a true interpretive compiler, all user source code and the compiler must be stored in core at run time. It is possible to modify the compiler to use a mass storage device (i.e., magnetic disk) to store user source code. At least one user has done this; however, such a procedure slows execution times and is not generally suitable for real-time experimentation. As released by Varian, basic contains no subroutines to support devices of the type needed in the laboratory (i.e., analog and digital I/O devices, control and sense lines, etc.).