The DSKY is a fifteen pound, 8" x 8" x 7" M.I.T.-designed and Raytheon-manufactured data entry and display device with nineteen keys and a twenty-one digit display. A unit like this was mounted into the control panel of each lunar module and two were found in each command module.
This was the astronaut's interface allowing access to the groundbreaking on board Apollo Guidance Computer, developed by MIT. It permitted the astronauts to collect and provide flight information and was very important in the precise landings on the moon needed for a successful mission.
Each different program had a two-digit code and commands were entered as two-digit numbers in a verb-noun sequence. These units were used in all Apollo missions, including Skylab and ASTP.
It is impossible to overestimate the importance of the DSKY interface and the AGC to the Apollo moon-landing program.