TECO was originally developed at MIT in around 1963 by Daniel L. Murphy for use on two PDP-1 computers, belonging to different departments, both housed in MIT's Building 26. On these machines, the normal development process involved the use of a Friden Flexowriter to prepare source code offline on a continuous strip of punched paper tape. Programmers of the big IBM mainframes customarily punched their source code on cards, using key punches which printed human-readable dot-matrix characters along the top of every card at the same time as they punched each machine-readable character. Thus IBM programmers could read, insert, delete, and move lines of code by physically manipulating the cards in the deck. Punched paper tape offered no such amenities, leading to the development of online editing.