The PDP-7 was a bookshelf-sized "minicomputer", with keyboard, magnetic and paper tape and printer I/O. According to Wikipedia, the first version of UNIX (then named Unics) was programmed in assembly on the PDP-7.
Despite this, I can't find much information about the PDP-7's assembly syntax nor instruction set. As only knowledge of the registers and instructions are required to write and interpret bytecode, this information is the most important for understanding PDP-7 code.
What instruction set was used by PDP-7 minicomputers?