According to Noyce and Moore, as well as David Brock and Joel Shurkin, the shift from bipolar transistors to Shockley diodes was unexpected.[37][38][36] Shockley initially planned to work on the mass production of diffusion bipolar transistors, but then set up a "secret project" on Shockley diodes, and in 1957 stopped all works on bipolar transistors.[39][40] The reasons for this turn are unknown.[36] According to Beckman's biographer, Shockley regarded his diode as an interesting scientific problem, and chose it, neglecting Beckman's commercial interests.[41]