in the computer history museum video celebrating the pdp restoration there is a mention of t square possibly being the first electronic drafting program and that it used the spacewar controllers spacewar apparently first ran in february in his mit phd thesis published in ivan sutherland explains he completed an early version of sketchpad that could draw parallel and perpendicular lines in november sutherland goes on to say somewhat before my first effort was working welden clark of bolt beranek and newman showed him a similar program running on a pdp it would be interesting to know what program that was