This report of Market Data Retrieval's second comprehensive survey of microcomputers and their use in grades K-12 presents information for the 1984-85 year for public, private, and Catholic schools in the United States. The survey findings are summarized in a brief introduction, and detailed data are presented in the 37 tables and 9 maps that accompany the narrative report. Areas covered include microcomputer use by school type, micro-intensity by grade level and type of school, brand distribution, and growth trends. Findings indicate that: (1) U.S. schools are now using 630,000 microcomputers, a 75% increase over the 1983-84 school year; (2) public school use of micros (85.1%) still exceeds private (46.4%) and Catholic school (63.4%) use; (3) senior high schools still lead the way with 94.6% using microcomputers, but junior high schools are now at 93.1% and elementary schools at 82.2%; (4) 94.2% of U.S. public school districts now use microcomputers for instruction (an increase of 86.1% over last year, and 41.7% over 4 years ago); (5) Apple computer remains the most common microcomputer brand, with a 50.9% share of the market; (6) Radio Shack is second with a 19.7% share and Commodore is third with 15.2%; (7) IBM had the fastest growth rate, moving to a 3.5% share of the market; (8) while the number of children sharing a computer has been reduced in both wealthy and poor schools (54 versus 73.3), wealthy schools are making improvements at a faster pace. State rankings, state profiles, and survey methodology and definitions are appended. (JB)