These two interim reports are the third and fourth in a series based on data from the 1,082 microcomputer-owning public and non-public elementary and secondary schools that responded to a survey of 1,600 schools (68%) between December 1982 and March 1983. Issue No. 3 presents comparable data on microcomputer ownership and use for schools in different regions and in cities, suburbs, and rural locations; for junior high and middle schools in comparison with elementary and high schools; and for schools serving students of varied socioeconomic backgrounds. Issue No. 4 focuses on the different patterns that schools have used to obtain microcomputers: the initiative of a single teacher, the effort of a building principal, the role of parent-teacher organizations, the leadership of school district and other school administrative personnel, and financial assistance from special grant programs. Data show how schools have changed in the way they have obtained microcomputers and how they have organized their use by students. (LMM)