The IBM Administrative Terminal System, also known as ATS/360[1], was an IBM contributed program which provided, for the end-user customer of IBM System/360 systems, a system which was quite similar to the proprietary IBM Service Bureau Corporation product, Call/ATS, which ran on IBM 1440 systems or on IBM System/360 DOS systems.
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ATS/360 provided comprehensive text and data tools including entry, archiving and retrieving, formatting and printing. Utilizing ATS/360, a large business could maintain all its end-user documents, revising and printing new versions of these as required. Also using ATS/360, a large law practice could maintain its client files, including witness statements and depositions, and several landmark legal decisions were significantly assisted using ATS/360.
Initially, ATS/360 supported only IBM 2741 terminals. Later, support was added by user groups for 2741 terminals with the "break feature" and for IBM 1050 terminals. The Magnetic Card Selectric Typewriter (MC/ST), which could emulate a 2741, was also supported.
ATS/360 was designed exclusively for IBM 2311 and IBM 2314 direct access storage facilities (for "working storage" and for "permanent storage") and for IBM 2400/3400 tape drives (for "offline storage" and for offline "format and print" tapes).
An IBM hardware RPQ provided the IBM 1403 Model N1 printer's TN print train with characters which simulated the IBM Selectric typewriter Courier 72 type ball characters identically, thereby allowing machine printed documents to be manually corrected, or for manually inserted text, as required.
An IBM program RPQ added support for the IBM 3330 direct access storage facility, and this RPQ was applied by most users of ATS/360 which had migrated to IBM System/370 processors.
Support beyond OS/370 VS/2 Release 1 (SVS) was not offered by IBM, but Peter Haas, formerly with Litton Systems Inc, and later with Amdahl Corp, added support for MVS in general, and for APs and MPs in particular, and a large number of ATS/360 systems thereby remained in use well into the MVS/370 era.
ATS/360 was very efficient in its use of main storage, and it was not uncommon to support quite a few terminals in a minimum size region.
ATS/360 was also very efficient in its use of system resources, and it had its own task dispatcher which worked seamlessly with PCP, MFT/MFT-II and MVT, for which it was originally designed, with SVS and, later, with Haas's support, with MVS.
ATS/360's input/output operations utilized EXCP exclusively. Task switching was accomplished asynchronously as an extension of ATS/360's EXCP appendages and synchronously as an extension of ATS/360's Type 1 SVC, SVC 255. Thereby, ATS/360 could support quite a number of online (terminal) and offline (peripheral) tasks even on PCP (which otherwise supported just a single task).
ATS/360 provided its own access methods and file formats. Offline "format and print" tapes could be printed using standard OS utilities as these tapes were compatible with BSAM.
ATS was later modified to run under CICS using 3270 terminals and marketed as the ATMS program product.