They look like earlier bronze era RF boards of some sort. I've got a few of these and I want to make sure they're nothing that anyone needs before they are sacrificed to the gods of Waste Management.
PSE is one clue. MB presumably means main or mother board. DP and GT are also information. One or more is potentially a game name. Maybe both? The date code on the board says 10-77, more info. It also sorta looks Atari-ish, but not really.
Search VAPS for Atari games circa mid-70's with the initials PSE, DP, or GT. Nothing jumps out.
Ok, search all games. Desert Patrol by Project Support Engineering. Shooter from 1977. Ding.
Search other games by PSE. Game Tree. Also a shooter. Also 1977. Similar cab. Ding ding ding.
My guess is a main backplane board for those two games.