One  INS8154N National Semiconductor Ram Input/Output Dip 40.  These were used in many vintage computers in the 70's. Miller Technology M80 SBC, Acorn 1, EMMA, and MK14s' just to name a few, many which are being replicated and need these to work.  These parts are unused in the factory tubes here in my own stock in the USA.  We do not sell Chinese counterfeit junk.