Before any rocket is launched it goes through a thorough series of checks and tests to make sure that when the countdown reaches zero it will rise upwards to the heavens in an orderly fashion, and ultimately end up where it needs to be. In the early years of the space program these checks were carried out manually by operators who sat at consoles, threw switches and looked at the results that flashed up on their consoles, and deciphered printed sheets full of data. As the rockets grew larger and more sophisticated the sheer amount and complexity of these tests started to outstrip the human brains capability to carry them out quickly and accurately. A system called ACE was developed, Automated Check Out Equipment. At the heart of the system was the RCA110A computer, and when hooked up to the spacecraft the system checked that everything had been put together correctly. Further to this it could carry out simulations, and it also monitored the health of the spacecraft right up to the last seconds of the countdown.