for the IBM 1400 series 1410 Processor Operating System (PR-155) for the 1410 and 7010 SHARE Operating System (SOS) – for the IBM 704 and 709 University of Michigan Executive System (UMES) – for the IBM 704, 709, and 7090) On S/360, S/370, and successor mainframes OS/360 and successors on IBM S/360, S/370, and successor mainframes OS/360 (first official OS targeted for the System/360 architecture) PCP (Primary Control Program, a kernel and a ground breaking automatic space allocating file system) MFT (original Multi-programming with a Fixed number of Tasks, replaced by MFT II) MFT II (Multi-Programming with a Fixed number of Tasks, had up to 15 fixed size application partitions, plus partitions for system tasks, initially defined at boot time but redefinable by operator command) MVT (Multi-Programming with a Variable number of Tasks, had up to 15 application regions defined dynamically, plus additional regions for system tasks) M65MP (MVT with support for a multiprocessor 360/65) OS/VS (port of OS/360 targeted for the System/370 virtual memory architecture (OS/370 is not the correct name for OS/VS1 and OS/VS2.) OS/VS has the following variations: OS/VS1 (Operating System/Virtual Storage 1, Virtual-memory version of OS/360 MFT II) OS/VS1 Basic Programming Extensions (BPE) adds device support and VM handshaking OS/VS2 (Operating System/Virtual Storage 2, Virtual-memory version of OS/360 MVT) OS/VS2 R1 (Called Single Virtual Storage (SVS), Virtual-memory version of OS/360 MVT but without multiprocessing support) OS/VS2 R2 through R3.8 (called Multiple Virtual Storage, MVS, eliminated most need for VS1). MVS/SE (MVS System Extensions) MVS/SP (MVS System Product) V1 MVS/370 refers to OS/VS2 MVS, MVS/SE and MVS/SP Version 1 MVS/XA (MVS/SP V2, supports S/370 Extended Architecture, 31-bit addressing) MVS/ESA (MVS supported Enterprise Systems Architecture, horizontal addressing extensions: data only address spaces called Dataspaces) MVS/SP V3 MVS/ESA SP V4 (a Unix environment was available for MVS/ESA SP V4R3) MVS/ESA SP V5 (the UNIX environment was bundled in this and all subsequent versions) OS/390 replacement for MVS/ESA SP V5 with some products bundled z/OS z/Architecture replacement for OS/390 with 64-bit virtual addressing Phoenix/MVS (Developed at Cambridge University) DOS/360 and successors on IBM S/360, S/370, and successor mainframes BOS/360 (early interim version of DOS/360, briefly available at a few Alpha & Beta System/360 sites) TOS/360 (similar to BOS above and more fleeting, able to boot and run from 2x00 series tape drives) DOS/360 (Disk Operating System (DOS), multi-programming system with up to 3 partitions, first commonly available OS for System/360)