IBM System/360: Семейство мэйнфреймов нового поколения

IBM mainframe computer family (1964–1977)

The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applications and a complete range of applications from small to large. The design distinguished between architecture and implementation, allowing IBM to release a suite of compatible designs at different prices. All but the only partially compatible Model 44 and the most expensive systems use microcode to implement the instruction set, featuring 8 bit byte addressing and fixed point binary, fixed point decimal and hexadecimal floating point calculations. The System/360 family introduced IBM's Solid Logic Technology (SLT), which packed more transistors onto a circuit card, allowing more powerful but smaller computers. The slowest System/360 model announced in 1964, the Model 30, could perform up to 34,500 instructions per second, with memory from 8 to 64 KB. High performance models came later. The 1967 IBM System/360 Model 91 could execute up to 16.6 million instructions per second. The larger 360 models could have up to 8 MB of main memory, The commercial release was piloted by another of Watson's lieutenants, John R. Opel, who managed the launch of IBM’s System 360 mainframe family in 1964. Application level compatibility (with some restrictions) for System/360 software is maintained to the present day with the System z mainframe servers.

By the early 1960s, IBM was struggling with the load of supporting and upgrading five separate lines of computers. These were aimed at different market segments and were entirely different from each other. A customer who purchased a machine to handle accounting, such as the IBM 1401, that was now looking for a machine for engineering calculations, such as the IBM 7040, had no reason to select IBM the 7040 was incompatible with the 1401 and they might as well have been from different companies. Customers were frustrated that major investments, often entirely new machines and programs, were required when seemingly small performance improvements were needed. In 1961, IBM assembled a task force to chart their developments for the 1960s, known as SPREAD, for Systems Programming, Research, Engineering and Development. In meetings at the New Englander Motor Hotel in Greenwich, Connecticut, SPREAD developed a new concept for the next generation of IBM machines. At the time, new technologies were coming into the market including the introduction of replacement of individual transistors with small scale integrated circuits and the move to an 8 bit byte from the former 6 bit oriented words. These were going to lead to a new generation of machines, today known as the third generation, from all of the existing vendors.

Producing a single machine with support for all of these features would border on impossible. Instead, the SPREAD concept was based on the separation of the defined feature set from its internal operation, with a family of machines with different performance and different internal designs. Specifically, depending on the machine, some instructions might not be directly supported in hardware, and would instead be completed using small programs, in an internal machine specific code, stored in read only memory, or what today is known as microcode. So a model intended for use with accounting might choose to implement the decimal math directly in hardware, and leave the floating point instructions to be handled by the subprograms. This would make floating point on such a system run (much) more slowly, but, critically, it would run. Likewise, a company purchasing a system for engineering support would choose a model with floating point hardware, and might use it from time to time to run their payroll. Using previous designs, the system that performed floating point would generally not have any support for decimal math all, and would require the customer to write such a package or buy another machine. This meant that a single lineup could have machines tailored to match the price and performance niches that formerly demanded entirely separate computer systems. This flexibility greatly lowered barriers to entry. With most other vendors customers had to choose between machines they might outgrow or machines that were potentially too powerful and thus too costly. In practice, this meant that many companies simply did not buy computers. Now, a customer could purchase a machine that solved a particular requirement, knowing they could change the models as their needs changed, without losing support for the programs they were already running. ), 85 (1969), 91 (1967, anticipated as the 92), 95 (1968), and 195 (1971). The 85 design was intermediate between the System/360 line and the follow on System/370 and was the basis for the 370/165. There was a System/370 version of the 195, but it did not include Dynamic Address Translation. The implementations differed substantially, using different native data path widths, presence or absence of microcode, yet were extremely compatible. Except where specifically documented, the models were architecturally compatible. The 91, for example, was designed for scientific computing and provided out of order instruction execution (and could yield "imprecise interrupts" if a program trap occurred while several instructions were being read), but lacked the decimal instruction set used in commercial applications. New features could be added without violating architectural definitions: the 65 had a dual processor version (M65MP) with extensions for inter CPU signalling; the 85 introduced cache memory. Models 44, 75, 91, 95, and 195 were implemented with hardwired logic, rather than microcoded as all other models. The Model 67, announced in August 1965, was the first production IBM system to offer dynamic address translation (virtual memory) hardware to support time sharing. "DAT" is now more commonly referred to as an MMU. An experimental one off unit was built based on a model 40. Before the 67, IBM had announced models 64 and 66, DAT versions of the 60 and 62, but they were almost immediately replaced with the 67 at the same time that the 60 and 62 were replaced with the 65. DAT hardware would reappear in the S/370 series in 1972, though it was initially absent from the series. Like its close relative, the 65, the 67 also offered dual CPUs. IBM stopped marketing all System/360 models by the end of 1977.

IBM's existing customers had a large investment in software that ran on second generation machines. Several System/360 models had the option of emulating the customer's existing computer using special hardware
IBM later added features and modified emulator programs to allow emulation of the 1401, 1440, 1460, 1410 and 7010 under the control of an operating system. The Model 85 and later System/370 maintained the precedent, retaining emulation options and allowing emulators to run under OS control alongside native programs.

System/360 (excepting the Models 20, 44 and 67) was replaced with the compatible System/370 range in 1970 and Model 20 users were targeted to move to the IBM System/3. (The idea of a major breakthrough with FS technology was dropped in the mid 1970s for cost effectiveness and continuity reasons.) Later compatible IBM systems include the 4300 family, the 308x family, the 3090, the ES/9000 and 9672 families (System/390 family), and the IBM Z series. Computers that were mostly identical or compatible in terms of the machine code or architecture of the System/360 included Amdahl's 470 family (and its successors), Hitachi mainframes, the UNIVAC 9000 series, Fujitsu as the Facom, the RCA Spectra 70 series, and the English Electric System 4. The System 4 machines were built under license to RCA. RCA sold the Spectra series to what was then UNIVAC, where they became the UNIVAC Series 70. UNIVAC also developed the UNIVAC Series 90 as successors to the 9000 series and Series 70. The IBM 5100 portable computer, introduced in 1975, offered an option to execute the System/360's APL. SV programming language through a hardware emulator. IBM used this approach to avoid the costs and delay of creating a 5100 specific version of APL. Special radiation hardened and otherwise somewhat modified System/360s, in the form of the System/4 Pi avionics computer, are used in several fighter and bomber jet aircraft. In the complete 32 bit AP 101 version, 4 Pi machines were used as the replicated computing nodes of the fault tolerant Space Shuttle computer system (in five nodes). The U. S. Federal Aviation Administration operated the IBM 9020, a special cluster of modified System/360s for air traffic control, from 1970 until the 1990s. (Some 9020 software is apparently still used via emulation on newer hardware.)

The System/360 series has a computer system architecture specification. channel with one bus cable and one tag cable. The initial use for this was the 2305 fixed head disk, which has 8 "exposures" (alias addresses) and rotational position sensing (RPS). Block multiplexer channels can operate as a selector channel to allow compatible attachment of legacy subsystems.

Being uncertain of the reliability and availability of the then new monolithic integrated circuits, IBM chose instead to design and manufacture its own custom hybrid integrated circuits. These were built on 11 mm square ceramic substrates. Resistors were silk screened on and discrete glass encapsulated transistors and diodes were added. The substrate was then covered with a metal lid or encapsulated in plastic to create a "Solid Logic Technology" (SLT) module. A number of these SLT modules were then flip chip mounted onto a small multi layer printed circuit "SLT card". Each card had one or two sockets on one edge that plugged onto pins on one of the computer's "SLT boards" (also referred to as a backplane). This was the reverse of how most other company's cards were mounted, where the cards had pins or printed contact areas and plugged into sockets on the computer's boards. Up to twenty SLT boards could be assembled side by side (vertically and horizontally, max 4 high by 5 wide) to form a "logic gate". Several gates mounted together constituted a box shaped "logic frame". The outer gates were generally hinged along one vertical edge so they could be swung open to provide access to the fixed inner gates. The larger machines could have more than one frame bolted together to produce the final unit, such as a multi frame Central Processing Unit (CPU).

The smaller System/360 models used the Basic Operating System/360 (BOS/360), Tape Operating System (TOS/360), or Disk Operating System/360 (DOS/360, which evolved into DOS/VS, DOS/VSE, VSE/AF, VSE/SP, VSE/ESA, and then z/VSE). The larger models used Operating System/360 (OS/360). IBM developed several levels of OS/360, with increasingly powerful features: Primary Control Program (PCP), Multiprogramming with a Fixed number of Tasks (MFT), and Multiprogramming with a Variable number of Tasks (MVT). MVT took a long time to develop into a usable system, and the less ambitious MFT was widely used. PCP was used on intermediate machines too small to run MFT well, and on larger machines before MFT was available; the final releases of OS/360 included only MFT and MVT. For the System/370 and later machines, MFT evolved into OS/VS1, while MVT evolved into OS/VS2 (SVS) (Single Virtual Storage), then various versions of MVS (Multiple Virtual Storage) culminating in the current z/OS. When it announced the Model 67 in August 1965, IBM also announced TSS/360 (Time Sharing System) for delivery at the same time as the 67. TSS/360, a response to Multics, was an ambitious project that included many advanced features. It had performance problems, was delayed, canceled, reinstated, and finally canceled again in 1971. Customers migrated to CP 67, MTS (Michigan Terminal System), TSO (Time Sharing Option for OS/360), or one of several other time sharing systems. CP 67, the original virtual machine system, was also known as CP/CMS. CP/67 was developed outside the IBM mainstream at IBM's Cambridge Scientific Center, in cooperation with MIT researchers. CP/CMS eventually won wide acceptance, and led to the development of VM/370 (Virtual Machine) which had a primary interactive "sub" operating system known as VM/CMS (Conversational Monitoring System). This evolved into today's z/VM. The Model 20 offered a simplified and rarely used tape based system called TPS (Tape Processing System), and DPS (Disk Processing System) that provided support for the 2311 disk drive. TPS could run on a machine with 8 KB of memory; DPS required 12 KB, which was pretty hefty for a Model 20. Many customers ran quite happily with 4 KB and CPS (Card Processing System). With TPS and DPS, the card reader was used to read the Job Control Language cards that defined the stack of jobs to run and to read in transaction data such as customer payments. The operating system was held on tape or disk, and results could also be stored on the tapes or hard drives. Stacked job processing became an exciting possibility for the small but adventurous computer user. A little known and little used suite of 80 column punched card utility programs known as Basic Programming Support (BPS) (jocularly: Barely Programming Support), a precursor of TOS, was available for smaller systems.

IBM created a new naming system for the new components created for System/360, although well known old names, like IBM 1403 and IBM 1052, were retained. In this new naming system, components were given four digit numbers starting with 2. The second digit described the type of component, as follows:
20xx: Arithmetic processors, for example the IBM 2030, which was the CPU for the IBM System/360 Model 30. 21xx: Power supplies and other equipment intimately associated with processors, for example the IBM 2167 Configuration Unit. 22xx: Visual output devices, for example the IBM 2250 and IBM 2260 CRT displays, and the IBM 2203 line printer for the System/360 model 20. 23xx: Direct access storage devices, for example the IBM 2311 and IBM 2314 disk drives, the IBM 2321 Data Cell;Main storage such as the IBM 2361 Large Capacity Storage (Core Storage, Large Core Storage or LCS) and the IBM 2365 Processor Storage. 24xx: Magnetic tape drives, for example the IBM 2401, IBM 2405 and IBM 2415. 25xx: Punched card handling equipment, for example the IBM 2501 (card reader), IBM 2520 (card punch); IBM 2540 (reader/punch) and IBM 2560 (Multi Function Card Machine or MFCM). 26xx: Paper tape handling equipment, for example the IBM 2671 paper tape reader. 27xx: Communications equipment, for example the IBM 2701, IBM 2705, IBM 2741 interactive terminal and the IBM 2780 batch terminal. 28xx: Channels and controllers, for example the IBM 2821 Control Unit, IBM 2841 and IBM 2844. 29xx: Miscellaneous devices, for example the IBM 2914 Data Channel Switch and the IBM 2944 Data Channel Repeater.

IBM developed a new family of peripheral equipment for System/360, carrying over a few from its older 1400 series. Interfaces were standardized, allowing greater flexibility to mix and match processors, controllers and peripherals than in the earlier product lines. In addition, System/360 computers could use certain peripherals that were originally developed for earlier computers. These earlier peripherals used a different numbering system, such as the IBM 1403 chain printer. The 1403, an extremely reliable device that had already earned a reputation as a workhorse, was sold as the 1403 N1 when adapted for the System/360. Also available were optical character recognition (OCR) readers IBM 1287 and IBM 1288 which could read Alpha Numeric (A/N) and Numeric Hand Printed (NHP/NHW) Characters from Cashier's rolls of tape to full legal size pages. At the time this was done with very large optical/logic readers. Software was too slow and expensive at that time. Models 65 and below sold with an IBM 1052 7 as the console typewriter. The 360/85 with feature 5450 uses a display console that was not compatible with anything else in the line; the later 3066 console for the 370/165 and 370/168 use the same basic display design as the 360/85. The IBM System/360 models 91 and 195 use a graphical display similar to the IBM 2250 as their primary console. Additional operator consoles were also available. Certain high end machines could optionally be purchased with a 2250 graphical display, costing upwards of US $100,000; smaller machines could use the less expensive 2260 display or later the 3270.

Punched card devices included the 2501 card reader and the 2540 card reader punch. Virtually every System/360 had a 2540. The 2560 MFCM ("Multi Function Card Machine") reader/sorter/punch, listed above, was for the Model 20 only. It was notorious for reliability problems (earning humorous acronyms often involving " Card Muncher" or "Mal Function Card Machine"). Line printers were the IBM 1403 and the slower IBM 1443. A paper tape reader, the IBM 2671, was introduced in 1964. It had a rated speed of 1,000 cps. There were also a paper tape reader and paper tape punch from an earlier era, available only as RPQs (Request Price Quotation). The 1054 (reader) and 1055 (punch), which were carried forward (like the 1052 console typewriter) from the IBM 1050 Teleprocessing System. All these devices operated at a maximum of 15.5 characters per second. The paper tape punch from the IBM 1080 System was also available by RPQ, but at a prohibitively expensive price. Optical character recognition (OCR) devices 1287 and later the 1288 were available on the 360's. The 1287 could read handwritten numerals, some OCR fonts, and cash register OCR paper tape reels. The 1288 'page reader' could handle up to legal size OCR font typewritten pages, as well as handwritten numerals. Both of these OCR devices employed a 'flying spot' scanning principle, with the raster scan provided by a large CRT, and the reflected light density changes were picked up by a high gain photomultiplier tube. Magnetic ink character recognition (MICR) was provided by the IBM 1412 and 1419 cheque sorters, with magnetic ink printing (for cheque books) on 1445 printers (a modified 1443 that used an MICR ribbon). 1412/1419 and 1445 were mainly used by banking institutions.

Despite having been sold or leased in very large numbers for a mainframe system of its era, only a few of System/360 computers remain—mainly as non operating property of museums or collectors. Examples of existing systems include:
The Computer History Museum in Mountain View, California, has a non working Model 30 on display, as do the Museum of Transport and Technology in Auckland, New Zealand, and the Vienna University of Technology in Austria. The University of Western Australia Computer Club has a complete Model 40 in storage. The KCG Computer Museum of Kyoto Computer Gakuin, Japan's first computer school in town, has an IBM System/360 Model 40 on display. Two IBM System/360 Model 20 processors along with numerous peripherals (forming two complete systems) located in Nuremberg, Germany, were purchased on eBay in April/May 2019 for €3,710 by two UK enthusiasts, Adam Bradley and Chris Blackburn, who, over the course of some months, moved the machine to Creslow Park in Buckinghamshire, United Kingdom. The system was in a small, abandoned building left untouched for decades, and apparently had been used in that building since all peripherals were still fully wired and interconnected. The systems are now in a dedicated machine room, and are undergoing restoration in preparation for public display in the future. The Living Computers: Museum + Labs has a 360 model 30. A running list of remaining System/360s that are more than just 'front panels' can be found at World Inventory of remaining System/360 CPUs.

This gallery shows the operator's console, with register value lamps, toggle switches (middle of pictures), and "emergency pull" switch (upper right of pictures) of the various models.