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 IBM System/360 Model 40 at the USDA | |
| Manufacturer | International Business Machines Corporation (IBM) |
|---|---|
| Product family | System/360 |
| Release date | April 7, 1964 |
| Discontinued | October 7, 1977 |
| Memory | 16–128 KB Core |
The IBM System/360 Model 40 was a mid-range member of the IBM System/360 family. It was announced on April 7, 1964, shipped in 1965, and withdrawn on October 7, 1977. [1] [2]
On April 7, 1964, IBM announced the IBM System/360, to be available in six models. [3] [4] [5] The 360/40 was first delivered in April 1965. [6]
The 360/30 and the 360/40 were the two largest revenue producing System/360 models, [7] accounting for over half of the units sold. [8]
Five models of the 360/40 were offered. [9] The D40, E40, F40, G40 and H40 were configured with 16K, 32K, 64K, 128K and 256K of core memory and correspondingly 16, 32, 64, 128 and 128 [NB 1] multiplexer subchannels. [9]
The H40 occupied "more floor space than the other models." [9] : p.5
| A typical, early, basic Model 40 system had the following configuration: [10] | |
|---|---|
| Model 40 processor | IBM 2040 Central Processing Unit *128 KB byte storage *storage protection feature *universal instruction set *one multiplexor channel *two selector channels *interval timer |
| Operator console | IBM 1052 Typewriter- Keyboard (usually assigned to 009 hexadecimal address) |
| Unit record device | IBM 1442 Card Reader-Punch (00A) or IBM 2540 Reader-Punch (00C & 00D) |
| Line printer | IBM 1443 Printer (00B) or IBM 1403 Printer (00E) |
| Disk storage | IBM 2311 Magnetic Disk Drives (190 & 191) or IBM 2314 Direct Access Storage Facility |
| Tape storage | IBM 2401 Magnetic Tape Units (180 & 181 for 7-track, and 182 & 183 for 9-track) |
| Telecommunications controller (If used in a telecommunications environment) | IBM 2701 Communication Controller |
Like most System/360 models the Model 40 is microprogrammed. The microcode is stored in transformer read-only storage (TROS), organized as up to 8192 words of 56 bits each. Standard microcode consists of up to 4096 words. The additional 4096 words are used for the 1401 or 1410 compatibility feature. [11]
With the additional Compatibility Feature hardware and Compatibility Support software under DOS/360, the IBM 1401/1440/1460 object programs can be run in the emulation mode, with little or no reprogramming. [12]
Although the cover of IBM's MVT Guide [13] indicates that even a 360/40 could run MVT, the IBM operating system used was usually the realistically sized DOS/360,[ citation needed ] because all but one model of the 360/40 had less than MVT's minimum memory requirements of 256KB. [14] [15]
The IBM System/360 Model 40 was developed at IBM Hursley [16] and manufactured at IBM's facilities in: Poughkeepsie, U.S., Mainz, Germany; and Fujisawa, Japan. [17]
A modified Model 40 ran CP-40, the ancestor of CP/CMS, which in turn was the progenitor of the VM line.
IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the computer market with the 7000 series and the later System/360, followed by the System/370. Current mainframe computers in IBM's line of business computers are developments of the basic design of the System/360.
In processor design, microcode serves as an intermediary layer situated between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer, also known as its machine code. It consists of a set of hardware-level instructions that implement the higher-level machine code instructions or control internal finite-state machine sequencing in many digital processing components. While microcode is utilized in Intel and AMD general-purpose CPUs in contemporary desktops and laptops, it functions only as a fallback path for scenarios that the faster hardwired control unit is unable to manage.
The IBM System/360 (S/360) is a family of mainframe computer systems announced by IBM on April 7, 1964, and delivered between 1965 and 1978. System/360 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 IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement.
The IBM 1400 series are second-generation (transistor) mid-range business decimal computers that IBM marketed in the early 1960s. The computers were offered to replace tabulating machines like the IBM 407. The 1400-series machines stored information in magnetic cores as variable-length character strings separated on the left by a special bit, called a "wordmark," and on the right by a "record mark." Arithmetic was performed digit-by-digit. Input and output support included punched card, magnetic tape, and high-speed line printers. Disk storage was also available.
The IBM Time Sharing System TSS/360 is a discontinued early time-sharing operating system designed exclusively for a special model of the System/360 line of mainframes, the Model 67. Made available on a trial basis to a limited set of customers in 1967, it was never officially released as a supported product by IBM. TSS pioneered a number of novel features, some of which later appeared in more popular systems such as MVS. TSS was migrated to System/370 and 303x systems, but despite its many advances and novel capabilities, TSS failed to meet expectations and was eventually canceled. The Resident Supervisor of TSS/370 was used as the basis for a port of UNIX to the IBM mainframe. TSS/360 also inspired the development of the TSS/8 operating system.
The IBM System/360 Model 30 was a low-end member of the IBM System/360 family. It was announced on April 7, 1964, shipped in 1965, and withdrawn on October 7, 1977. The Model 30 was designed by IBM's General Systems Division in Endicott, New York, and manufactured in Endicott and other IBM manufacturing sites outside of U.S.
The IBM System/360 Model 67 (S/360-67) was an important IBM mainframe model in the late 1960s. Unlike the rest of the S/360 series, it included features to facilitate time-sharing applications, notably a Dynamic Address Translation unit, the "DAT box", to support virtual memory, 32-bit addressing and the 2846 Channel Controller to allow sharing channels between processors. The S/360-67 was otherwise compatible with the rest of the S/360 series.
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System Generation (SysGen) is a two-stage process for installing or updating OS/360, OS/VS1, OS/VS2 (SVS), OS/VS2 (MVS) and chargeable systems derived from them. There are similar processes for, e.g., DOS/360, which this article does not cover. Also, some of the details have changed between releases of OS/360 and many details do not carry over to later systems.
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Mike Flinders, who also worked at Hursley where the 360/40 was designed
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