IBM System/370

IBM System/370
Name	IBM System/370
Developer	IBM
Manufacturer	IBM
Family	System/360
Release	1970
Discontinuation	1990s
Cpu	IBM mainframe processors
Memory	core memory, semiconductor memory
Os	OS/VS1, OS/VS2, MVS, VM, TSS/370, DOS/VS
Predecessor	System/360
Successor	Enterprise System/9000

IBM System/370 The IBM System/370 was a family of mainframe computers introduced in 1970 as a successor to the System/360, providing enhanced processor features, expanded memory and input/output architectures, and formalized support for virtual memory. Featuring models ranging from entry-level installations to large-scale datacenter processors, the System/370 became central to commercial computing, influencing mainframe deployments at institutions such as AT&T, Bank of America, United States Postal Service, Federal Reserve Bank, and major universities. Its ecosystem encompassed operating systems, languages, and tools tied to organizations like DEC, UNIVAC, Control Data Corporation, Bell Labs, and software firms including Microsoft (early collaborations), SAP, and Oracle Corporation partners.

History and development

IBM announced the System/370 in 1970 as the successor to the System/360, building on architectural continuity established under the leadership of figures associated with Thomas J. Watson Jr. and engineering teams influenced by research at Hursley and laboratories akin to IBM Research. Development paralleled industry shifts led by companies such as Digital Equipment Corporation and initiatives like Project MAC at MIT. The 370 series adopted semiconductor memory trends first driven by firms like Fairchild Semiconductor and navigated standards debates involving institutions like ANSI and ISO. Major milestones included the introduction of virtual memory support in later releases influenced by academic work from University of Cambridge and Stanford University researchers and operational field trials with clients including General Electric and AT&T Long Lines.

Architecture and instruction set

The System/370 architecture maintained backward compatibility with System/360 while introducing enhancements to support virtualization and expanded addressing. Its instruction set architecture (ISA) comprised fixed-length opcodes with binary-coded formats, reflecting design practices similar to those at Bell Labs and engineers influenced by instruction set studies from Irvine and Maurice Wilkes-era projects. Memory management added a virtual memory facility using translation lookaside buffers and segmentation/paging concepts parallel to research at Carnegie Mellon University and University of California, Berkeley. I/O operated via channel subsystem designs analogous to techniques used by Control Data Corporation and interfaced with peripherals from vendors like Memorex and Hewlett-Packard.

Models and hardware variations

The System/370 line spanned small to high-end models, including processors derived from earlier System/360 units and later high-performance members comparable to offerings from CDC and Honeywell. Notable family members included low-end entry systems for regional installations and large machines with multiple processors, expanded core and semiconductor memory, and peripheral channel enhancements used by organizations like NASA and Lockheed. Hardware variations incorporated microcode changes influenced by developments at IBM Hursley and partnerships with suppliers such as Intel for semiconductor components, while high-reliability units paralleled redundancy strategies used by Siemens and Fujitsu in enterprise systems.

Operating systems and software ecosystem

The System/370 supported a diverse software ecosystem: IBM-developed operating systems such as OS/VS1, OS/VS2 (which evolved into MVS), VM (virtual machine), TSS/370, and DOS/VS, alongside third-party systems and development tools from companies like Applied Data Research and Cullinet. Programming languages prevalent on the platform included COBOL, FORTRAN, PL/I, and assembly language, with compilers and runtime systems developed in conjunction with institutions like Bell Labs and commercial vendors such as SAS Institute and Sperry. Database systems and transaction processing middleware akin to products from IMS and CICS supported enterprise workloads for banks, airlines, and government agencies including United Airlines and IRS installations.

Performance, reliability, and virtualization

System/370 designs emphasized throughput, fault tolerance, and availability suitable for mission-critical environments similar to practices at AT&T and NASA. Performance improvements derived from faster cycle times, expanded memory, and channel I/O innovations influenced by DEC and Hewlett-Packard research. Reliability and recoverability features paralleled standards pursued by National Bureau of Standards and incorporated error detection/correction hardware akin to techniques from Bell Labs. Crucially, the System/370 family formalized virtualization support through the VM operating system and hardware facilities, shaping virtualization work at institutions like Xerox PARC and influencing later hypervisor developments at companies such as VMware.

Legacy and influence on modern computing

The System/370 left a lasting legacy in enterprise computing, setting standards for backward compatibility, virtualization, and large-scale transaction processing adopted by successors and competitors including Unisys, Bull, Fujitsu, and later x86 server ecosystems from Intel and AMD. Its operational models influenced banking, airline reservation systems, and government data centers, while academic and industrial research at MIT, Stanford University, and Carnegie Mellon University extended its virtualization and operating system concepts into modern cloud and hyperconverged infrastructure developed by firms such as Amazon Web Services and Google. The System/370 lineage persisted through IBM mainframe families and inspired legal, standards, and commercial practices involving organizations like IEEE and ISO.

Category:IBM mainframes