Help needed identifying boards

The board "HP-02116-6119_H_741_6" is identical in form,layout and bus connections (as far as can be discerned from the photo) to the time base generator board in my HP 2116C computer, although the part number in the upper left corner of my board is different (12539-60001). According to the manual for the 12539 from Al's site the 12539 is for the 2100,2114,2115 and 2116 computers. There seems to be some confusion between the 'interface kit' number and the HP part number, perhaps the version you have is earlier, for the 2116 and before the 2100 existed. (My 12539 is from ~1971,72 based on the IC date codes.) It is, as Joe said, a programmable timed interrupt generator. Many of the ICs on the board are (obsolete,difficult to find(?)) CTL logic as per discussion of several weeks ago. Given the 16 transistors/component sets on the "HP-12604-60001" I'd guess it's a 16 bit I/O port or dual 8-bit I/O port (also for the 21xx machines).