following year on 12 September 1984. New features Among the new/optional features for the 4361 were: Auto-Start—automatically turns on the processor by telephone via the Remote Operator Control Facility or at a predetermined time and day of the week. The processor powers on and proceeds with initial microcode load, sets the clock and loads the system. APL keyboard A Workstation Adapter that includes support for terminals with APL keyboards, supporting the APL syntax and symbols. High-Accuracy Arithmetic Facility While Floating-Point Arithmetic capability has long been part of computing history, and was present in System/360, this feature's advancement, conceptualization of which, as Karlsruhe Accurate Arithmetic, had been under development for decades, was implemented as an optional feature on the 4361. The 4361 was withdrawn on 17 February 1987. IBM 4381 The IBM 4381 had a greater longevity than any of the above systems. Model Groups 1 & 2 were announced Sep 15, 1983 and withdrawn on 11 February 1986. Model Group 3 was announced on 25 October 1984 and withdrawn on 11 February 1986. Model Groups 11, 12, 13 & 14 were announced on 11 February 1986. Model Groups 21, 22, 23 & 24 were announced on 19 May 1987 and withdrawn on 19 August 1992. Operating systems New releases of: Disk Operating System/Virtual Storage Extended (DOS/VSE) Virtual Machine Facility/370 (VM/370) Release 6 Operating System/Virtual Storage 1 (OS/VS1) Release 7 supported the 4300 series as well as other System/370-compatible processors. For the 4321 and 4331: Small Systems Executive/Virtual Storage Extended (SSX/VSE), a simplified version of the DOS/VSE operating system for the IBM 4321 and IBM 4331 processors. Other Hughes Aircraft Company was the first IBM customer to install Endicott's initial IBM 4341 processor The IBM 4331 Model 2 was developed by the Boeblingen lab and manufactured in Endicott. The IBM 4341 Model 2 was developed by the intermediate systems group, and manufactured by SPD, in Endicott. Subsequent processors had development and manufacturing activities in Endicott, Havant, Boeblingen, Valencia, and Sumare. See also List of IBM products IBM System/360 IBM System/370 Karlsruhe Accurate Arithmetic (KAA) for the IBM 4361 Molly-guard Notes References Further reading (NB. Describes the 4381.) External links IBM Archives: Mainframes product profiles Request a login to Living Computers: Museum + Labs IBM 4361. 4300 series 32-bit computers