Fortran Subroutines for the PDP-12

This document outlines a package of eight subroutines and functions, written in FORTRAN and SABR, designed to enable real-time control of the PDP-12's peripheral hardware. The supported features include the KW12-A clock, display scope (VR-12), sense switches, external lines, relays, and left switches. While these routines simplify programming by allowing control from a high-level language, they do introduce a minimum sampling interval of approximately 4 msec. The document includes technical descriptions for each subroutine (CLKSET, CLKRUN, RELAY, DISP, ISNS, IEXL, IADC, ILSW), alongside a demonstration program, 'HISTOGRAM,' and complete assembly listings for the subroutines.