Editing Sketchpad (section)

== Software ==
[[File:Sketchpad N-Component Element.png|thumb|The geometric data or "N-component element" for a straight line is composed of addresses to two other N-component elements representing the end points of the line, which each contain an X and Y coordinate.<ref name=IES-thesis></ref>]]

Sketchpad was the earliest program ever to use a complete [[graphical user interface]].<ref name="SearsJacko2007"/>

The clever way the program organizes its [[Geometry|geometric]] data pioneered the use of ''master'' ([[Object (computer science)|objects]]) and ''occurrences'' ([[Instance (computer science)|instances]]) in computing and pointed forward to [[object-oriented programming]]. The main idea was to have master drawings which can be instantiated into many duplicates. When a master drawing is changed, then all instances change also.

Geometric [[Constraint programming|constraints]] was another major invention in Sketchpad, letting a user easily constrain geometric properties in the drawing: for instance, the length of a line or the angle between two lines could be fixed.

As a trade magazine said, clearly Sutherland "broke new ground in 3D computer modeling and visual simulation, the basis for computer graphics and CAD/CAM".<ref name=Penton>{{cite news |url=http://americanmachinist.com/cadcam-software/cadcam-hall-fame |title=The CAD/CAM Hall of Fame |work=American Machinist |publisher=Penton Media |date=November 1, 1998 |access-date=March 18, 2013}}</ref> Very few programs can be called precedents for his achievements. [[Patrick J. Hanratty]] is sometimes called the "father of CAD/CAM"<ref>{{cite news |title=Patrick Hanratty spotlight |url=http://www.ics.uci.edu/community/news/spotlight/spotlight_hanratty.php |date=October 18, 2012 |publisher=The Regents of the University of California |access-date=March 17, 2013}}</ref> and wrote PRONTO, a [[numerical control]] language at [[General Electric]] in 1957, and wrote CAD software while working for [[General Motors]] beginning in 1961. Sutherland wrote in his thesis that [[BBN Technologies |Bolt, Beranek and Newman]] had a "similar program"<ref name=IES-thesis>{{cite web |last1=Sutherland |first1=Ivan Edward |author1-link=Ivan Sutherland |title=Sketchpad: A man-machine graphical communication system (courtesy Computer Laboratory, University of Cambridge UCAM-CL-TR-574 September 2003) |publisher=Massachusetts Institute of Technology |date=January 1963 |url=http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-574.html |access-date=2006-12-26}}</ref> and [[T-Square (software)|T-Square]] was developed by [[Peter Samson]] and one or more fellow MIT students in 1962, both for the [[PDP-1]].<ref>{{cite web |title=The Mouse that Roared: PDP-1 Celebration Event (running time: 01:53:46) |date=15 May 2006 |url=http://archive.computerhistory.org/resources/moving-image/DEC/PDP-1_Online/dec.the_mouse_that_roared_pdp_1_celebration_event.lecture.2006.102654189.wmv |website=[[Computer History Museum]] |access-date=2013-03-14}}</ref>

The [[Computer History Museum]] holds [[Listing (computer)|program listings]] for Sketchpad.<ref>{{cite web |last1=Sutherland |first1=Ivan E. |author1-link=Ivan Sutherland |date=1963 |title=Sketchpad listings |url=https://www.computerhistory.org/collections/catalog/102726903 |access-date=2021-10-30}}</ref>