QCHESS,
Quigley's algebraic chess program by Edward John Quigley, originally written in the 70s for the PDP-8 in Basic, and later ported to several different computers.
Abstract
from PDP-8 Catalog, 1978 1
QCHESS is a Chess game written in BASIC that uses an algorithmic model of the game of Chess. The program as submitted to DECUS represents the end of about two years of work. Originally written for the PDP-8, QCHESS has been run on several different computers.