Simple Memory Extension Utility for FORTH
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
This article describes a method of extending a FORTH interpreter/compiler to handle executable code exceeding 64K bytes in a 16-bit environment. Traditionally, only 64K of code space is available for use in a 16-bit FORTH system. Elaborate, overlay systems are normally employed to supply memory space for additional words or programs. The method described here alters the FORTH nucleus or application program to allow normal FORTH coding procedures to use available memory over the 64K limit for executable code. This is accomplished by defining two additional words: "O:" (for "overlay:") and "O;" (for "overlay;") which are directly analogous to the defining words ":" and ";".