Editing Dartmouth BASIC (section)

===Initial version===
The project officially started in September 1963. The goal was to develop the language and operating system on an off-the-shelf computer.{{sfn|Kiewit|1971|p=9}} In early 1964, they approached the [[National Science Foundation]] (NSF) for funding. The NSF sent the proposals, one for the time sharing system and another for the language, out for peer review. The reviews invariably suggested they did not understand the difficulty of what they were attempting. In spite of these negative comments, the NSF went ahead with both grants. Educational discounts available from [[General Electric]] led to the purchase of a [[GE-225]] computer, in an era when not "going IBM" was still fraught with peril.{{sfn|Kemeny|Kurtz|1985|p=5}}

The GE-225 was paired with the much simpler [[DATANET-30]] (DN-30) machine and a [[hard drive]] connected to both machines in order to share programs.{{sfn|Kurtz|1981|p=520}} The DN-30 lacked any programming documentation at the time, as it was never intended to be shipped from the factory without a program already installed.{{sfn|Kemeny|Kurtz|1985|p=5}} It included one key feature, [[direct memory access]] (DMA) access to the larger GE machines. This meant small messages could be quickly passed back and forth between the machines, allowing commands typed by the user to be immediately performed by the 225.<ref name=DN30Ref>{{cite book |last=General Electric Computers |title=DATANET-30 Programming Reference Manual |year=1965 |url=http://dtss.dartmouth.edu/scans/D-30%20Manuals/D-30manual.pdf}}</ref>

The system would work by having the DN-30 run the terminals and save the user's work to the disk. When the user typed <code>RUN</code>, the DN-30 would use DMA to send that command to the GE-225. The 225 would read that file, compile it, run it, and pass back the results to the DN-30 which would print the output on the terminal.<ref>[https://web.archive.org/web/20070808230115/http://www.dtss.org/index.php Dartmouth Time Sharing System (DTSS). March 1995].  Retrieved 27 May 2016</ref>

In the summer of 1963, pending the purchase of the computer, GE provided access to one of their GE-225s. Kemeny began working on a prototype compiler. Students Michael Busch and John McGeachie began working on the operating system design that fall. Both the language and the OS were extensively modified during this period, although the basic goals remained the same and were published in a draft form that November.{{sfn|Kurtz|1981|p=520}}

The school's machine arrived in the last week of February 1964,{{sfn|Kemeny|Kurtz|1968|p=224}} was operational by mid-March,{{sfn|Kiewit|1971|p=10}} 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.{{sfn|Kemeny|Kurtz|1968|p=224}} The language was developed in parallel on borrowed time on another 225 machine.{{sfn|Kemeny|Kurtz|1968|p=225}} 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 Kemeny and John McGeachie ran the first BASIC program on 1 May 1964 at 4 a.m. [[Eastern Time Zone|ET]].{{sfn|Kiewit|1971|p=10}}

It is not completely clear what the first programs were. Many sources, including Dartmouth, claim it was this simple program:<ref>{{cite web |url=https://www.dartmouth.edu/its-tools/archive/history/timeline/1960s.html |title=The 1960s |website=Dartmouth ITS}}</ref>

 PRINT 2 + 2

A later history of the language states that two programs were typed in at the same time, one by Kemeny and one by another unnamed programmer. They typed in their programs, typed {{code|RUN}} at the same time, and received the correct results.{{sfn|Kemeny|Kurtz|1985|pp=16,22}} Kurtz was an early riser and had already gone home and "missed all the fun."{{sfn|Kemeny|Kurtz|1985|p=16}}

Over the next month the system was tested by having a numerical analysis class test programs on the system. During this period, the machine remained running properly for an average of five minutes.{{sfn|Kemeny|Kurtz|1968|p=226}} The problems were rapidly addressed, and in June it was decided to increase the number of terminals to eleven. It was around this time that a faster GE-235 replaced the 225. By the fall, 20 terminals were in use.{{sfn|Kurtz|1981|p=520}}

GE began to refer to the combination of GE-235 and DN-30 as the GE-265,{{sfn|Kemeny|Kurtz|1985|p=21}} adding their model numbers together. GE built about 75 additional examples of the GE-265,{{sfn|Kemeny|Kurtz|1985|p=22}} many for their [[service bureau]] business. GE referred to these as their Mark I time-sharing systems.{{sfn|Kurtz|1981|pp=532,534}}