Modv-Choice

This document serves as a library write-up for the MODV program (used with 8K FOCAL '69). MODV is designed to automatically store variables in "field one" alongside the text, eliminating the need for a user function like FNEW.

Key features and functionalities include:

• Two Versions: The program can be generated in either a "General" version (software protects the upper page of field one) or an "N.B.L." version (does not protect the last page of field one).
• Echo Suppression: Includes a feature to suppress echo on input from a keyboard or low-speed reader to prevent input buffer overflow, controllable via the switch register.
• Compatibility: Operates as an overlay and includes specific procedures for loading and saving with a Disk Monitor.
• Functional Differences: MODV modifies standard FOCAL behavior, such as producing descending-order variable dumps, changing specific error codes, and separating the "Erase" and "Erase All" functions.
• Customization: Provides notes on adding assembly language subroutines and instructions for using it with a 4-word overlay.

The remainder of the document contains the technical assembly code for the program, including subroutines for memory management, terminal input/output, and dialogue handling.