Use of the Disk File on Stretch The paper begins by briefly describing the Stretch (IBM 7030) computer with special emphasis given to the organization and operation of its input-output equipment. Physical characteristics of the two-disk system (4,194,304 72-bit words, 8 usec-per-word transmission rate, etc.) are noted. Timing limitations due to arm motion and disk rotation are discussed. Applications of disk usage are discussed separately for problem programs and for systems programs such as compilers and the supervisory program. Approximately 260,000 words of disk storage are reserved for the storage of systems programs and the subroutine library. Problem programs, however, are not currently filed on the disk. Certain programming techniques are discussed for transmitting words between disk and core storage with minimum delaying and interruption of the arithmetic unit. Dumps on disk are considered for both recovery from computer malfunction and for mathematical or physical developments during the calculation. Some comments are made regarding the reliability, economics, utility and weaknesses or limitations of the disk system. Several possible future applications are noted which appear to have disk connotations. CACM October, 1963 Carlson, B. G. Voorhes, E. A. CA631030 JB March 13, 1978 4:28 PM 695 5 695 695 5 695 695 5 695