Blended learning is designed to increase learning potential and is more commonly found than pure CALL (Pegrum 2009: p. 27). See Davies "et al." (2011: Section 1.1, "What is CALL?"). See also Levy & Hubbard (2005), who raise the question "Why call CALL "CALL"?" CALL dates back to the 1960s, when it was first introduced on university mainframe computers. The PLATO project, initiated at the University of Illinois in 1960, is an important landmark in the early development of CALL (Marty 1981). The advent of the microcomputer in the late 1970s brought computing within the range of a wider audience, resulting in a boom in the development of CALL programs and a flurry of publications of books on CALL in the early 1980s. Dozens of CALL programs are currently available on the internet, at prices ranging from free to expensive, and other programs are available only through university language courses. There have been several attempts to document the history of CALL. Sanders (1995) covers the period from the mid-1960s to the mid-1990s, focusing on CALL in North America. Delcloque (2000) documents the history of CALL worldwide, from its beginnings in the 1960s to the dawning of the new millennium. Davies (2005) takes a look back at CALL's past and attempts to predict where it is going. Hubbard (2009) offers a compilation of 74 key articles and book excerpts, originally published in the years 1988-2007, that give a comprehensive overview of the wide range of leading ideas and research results that have exerted an influence on the development of CALL or that show promise in doing so in the future. A published review of Hubbard's collection can be found in "Language Learning & Technology" 14, 3 (2010). Butler-Pascoe (2011) looks at the history of CALL from a different point of view, namely the evolution of CALL in the dual fields of educational technology and second/foreign language acquisition and the paradigm shifts experienced along the way. See also Davies et al. (2011: Section 2, "History of CALL"). During the 1980s and 1990s, several attempts were made to establish a CALL typology. A wide range of different types of CALL programs was identified by Davies & Higgins (1985), Jones & Fortescue (1987), Hardisty & Windeatt (1989) and Levy (1997: pp. 118ff.). These included gap-filling and Cloze programs, multiple-choice programs, free-format (text-entry) programs, adventures and simulations, action mazes, sentence-reordering programs, exploratory programs—and "total Cloze", a type of program in which the learner has to reconstruct a whole text.