According to Noyce and Moore, as well as David Brock and Joel Shurkin, the shift from bipolar transistors to Shockley diodes was unexpected. 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. The reasons for this turn are unknown. According to Beckman's biographer, Shockley regarded his diode as an interesting scientific problem, and chose it, neglecting Beckman's commercial interests.