This is a PDP-8/I computer. This computer was model was introduced in 1968 as the sucessor to the original PDP-8 and was the first to be made with IC's. It was made of the new M series simple module boards similar in function to the R series ones used in earlier machines except now made with IC's and somewhat more logic on each card. This machine required an expense wirewrap backplane to connect all the cards so later machines likes the PDP-8/E started using larger cards with a common bus to reduce the interconnect.
The pictures below come from the two machines I have. Both have 8K core, one had the high speed paper tape reader/punch interface. One was made in March 1972, the other has a lower serial number and was probably made in 1970.
Documents related to PDP-8/I