FR, FDIS and FADC for PDP-12 Input/Output

This document details three specific patches designed for PS/8 FOCAL on the PDP-12 system. These include:

• FADC: A function to sample analog-to-digital converters, taking the decimal channel number as an argument.
• FDIS: A function to display graphics on the PDP-12 scope, requiring X and Y coordinates.
• FR: A routine for sampling sense switches and operating the PDP-12 relays, which replaces the standard FATN routine in FOCAL.

The document includes the functional calls, error code descriptions for invalid input ranges, instructions for assembling the source code, and a provided PAL-8 assembly listing.