The machine arrived in the last week of February 1964, was operational by mid-March, and officially handed over on 1 April. By that point, the operating system design was already well developed. Most of the student programmers working on the operating system did so for 50 hours a week, in addition to their normal course load. The language was developed in parallel on borrowed time on another 225 machine. The OS was completed in April, and the entire system running on three Model 33 terminals was ready by the end of the month. John Kemény and John McGeachie ran the first BASIC program on 1 May 1964 at 4 a.m. ET.