41. They soon built a large analog computer for the task, but found that it was inaccurate and inflexible. 42. It was essentially an analog computer , and bombardiers were trained in great secrecy on how to use it. 43. Steele developed the concept for the DIDA, which would entail implementing an analog computer using only digital elements. 44. Some analog computers work using logarithms. 45. Its internal circuit was a classic analog computer state variable " loop ", which provided outputs in quadrature. 46. The earliest grade crossing predictors used analog computers to perform this calculation, but modern equipment uses digital microprocessors. 47. Project Cyclone was an analog computer developed by Reeves in 1950 for the analysis and design of dynamic systems. 48. Analog computers were widely used in scientific and industrial applications where digital computers of the time lacked sufficient performance.49. Most practical mechanical analog computers of any significant complexity used rotating shafts to carry variables from one mechanism to another. 50. The FERMIAC was an analog computer invented by physicist Enrico Fermi in 1947 to aid in his studies of neutron transport.