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The Sort/Merge utility is a mainframe program to sort records in a file into a specified order, merge pre-sorted files into a sorted file, or copy selected records. Internally, these utilities use one or more of the standard sorting algorithms , often with proprietary fine-tuned code.
The operation of SORT is directed by control statements, which are largely compatible among various IBM and third-party sort programs. The SORT or MERGE statement defines the sort keys— the fields on which the data is to be sorted or merged. This statement identifies the position, length, and data type of each key.
Line commands (which apply only to specific line(s)) such as copy, move, repeat, insert, exclude, delete, text flow, text split are entered by over-typing the line number fields with a one or two character code representing the command to be applied at that line followed by an optional number which further modifies the supplied command.
External sorting algorithms generally fall into two types, distribution sorting, which resembles quicksort, and external merge sort, which resembles merge sort. External merge sort typically uses a hybrid sort-merge strategy. In the sorting phase, chunks of data small enough to fit in main memory are read, sorted, and written out to a temporary ...
In the early 1990s a popular solution to link PCs with the mainframes was the Irma board, an expansion card that plugged into a PC and connected to the controller through a coaxial cable. 3270 simulators for IRMA and similar adapters typically provide file transfers between the PC and the mainframe using the same protocol as the IBM 3270 PC.
VME (Virtual Machine Environment) is a mainframe operating system developed by the UK company International Computers Limited (ICL, now part of the Fujitsu group). Originally developed in the 1970s (as VME/B, later VME 2900) to drive ICL's then new 2900 Series mainframes, the operating system is now known as OpenVME incorporating a Unix subsystem, and runs on ICL Series 39 and Trimetra [1 ...
A polyphase merge sort is a variation of a bottom-up merge sort that sorts a list using an initial uneven distribution of sub-lists (runs), primarily used for external sorting, and is more efficient than an ordinary merge sort when there are fewer than eight external working files (such as a tape drive or a file on a hard drive).
When the operator [p] selects the Load function, the system performs a System Reset, sends a Read IPL [q] channel command to the selected device in order to read 24 bytes into locations 0-23 and causes the channel to begin fetching CCWs at location 8; the effect is as if the channel had fetched a CCW with a length of 24, and address of 0 and ...