General Microelectronics introduced the first commercial PMOS circuit in 1964, a 20-bit shift register with 120 MOSFETs – at the time an incredible level of integration.[5] The attempt by General Microelectronics in 1965 to develop a set of 23 custom integrated circuits for an electronic calculator for Victor Comptometer[5] proved to be too ambitious given the reliability of PMOS circuits at the time and ultimately led to the demise of General Microelectronics.[6] Other companies continued to manufacture PMOS circuits such as large shift registers (General Instrument)[7] or the analogue multiplexer 3705 (Fairchild Semiconductor)[8] which were not feasible in bipolar technologies of the day.