ISR11 S0CCER - A Concordance Program chapter Guy E. Hochgesang Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. 111-15 TSX $I[OCRerr]RDY,[OCRerr] TSX TM[OCRerr],O. B. SPECT? [OCRerr]PECT?2 is a t[OCRerr]pe sorting routine) modified from an earlier program c[OCRerr]l1ed SMERSH[OCRerr]) written by Michael Lesk of the SM[OCRerr]T project. SMERSH in turn is a modified version of SWISH , written at the Mitre Corporation in 1962. SPECTR does a tape merge sort, using the data channel traps, with internal radix exchange sorting. Because the efficiency of the sort depends highly on the amount cf memory available, SPECTR uses the area between the program and common breaks for buffer space, and attempts to enlarge this area by dumping as much core as possible onto B[OCRerr]. Sorting by SPECTR is done in two basic steps. First the input tape is read and converted into sorted sequences. The keys upon which items are sorted are converted according to the collating sequence given in the CVRT table before sorting, and are restored during the last pass. A[OCRerr]ter the blocks of items are sorted they are written onto the first set of scratch tapes. The second step consists of merging the sorted sequences from one set of scratch tapes onto the other. These merge passes are repeated until the sorted sequences are merged onto one output tape. The messages printed by SPECTR give the following information: the input tape unit, the scratch tape units, the occurrences of an E[OCRerr]F on the input tape, the number of items and records to be sorted, the number of merge passes and sorted sequences, the maxizrrurn record capacity (computed 2. SPECTR: Smersh Program Edited by Change Tape Reads 3. SMERSH: Stolen from Mitre, Extensively Revised Sort-Harvard [OCRerr]. SWISH: Sorting With[OCRerr]Incredible Speed-Hollerith -