IBM 303X

The IBM 303X[Note 1] is a discontinued line of mainframe computers, the first model of which, the IBM 3033 Processor, nicknamed "The Big One", was introduced March 25, 1977.[1]

IBM 303X
IBM 3033 frame, 3036 console (table) and 3277 terminals
ManufacturerInternational Business Machines Corporation (IBM)
Product familyIBM 3031
IBM 3032
IBM 3033
Release date1977
DiscontinuedFebruary 5, 1985 (all three 303X)
SuccessorIBM 308X
IBM 3033 and peripherals

Two additional processors, the 3031 and the 3032, were announced on October 6, 1977.[2][3]

All three 303X systems were withdrawn on February 5, 1985.

Features

The CPUs feature instruction pipelining, "several instructions can be pre-fetched while one is being executed". "Processor storage ... is four-way interleaved" resulting in "a significantly faster data rate than... non-interleaved". Each of the three systems includes, as a standard feature, a Dual-display console, the newly announced IBM 3036. The systems consume less than half the floor space of a System/370 with an equal amount of computer memory and an identical number of channels because "the channels are physically integrated within the processor mainframe."[1][2][3] Each group of six channels has its own microprogrammed channel processor, called a Channel Director. The Director is internally very similar to a System/370 Model 158, running special channel microcode.

The initial announcement of the 3033 also introduced new operating system versions "MVS/System Extensions[1][Note 2] (MVS/SE) and VM/System Extensions (VM/SE)."

303X as successor to System 370

Beginning in 1977, IBM began to introduce new systems, using the following descriptions:

  • "A compatible member of the System/370 family."[2]
  • "System/370 Compatible - 303(1/2/3)"[4]
  • "the System/370 3033 Processor."[1][Note 3]

Competing compatibles

At this time, other companies, known as plug compatible manufacturers (PCMs), were competing with IBM by producing IBM-compatible systems.[5] By the late 1970s and early 1980s, patented technology allowed Amdahl IBM-compatible mainframes of this era to be completely air-cooled, unlike IBM systems that required chilled water and its supporting infrastructure[6]— the 8 largest of the 18 models of the ES/9000 systems introduced in 1990 were water-cooled; the other ten were air-cooled.[7]

"The 3033 model, introduced in response to competition from the Amdahl Corporation, represented almost a 100 percent improvement in performance over the previous model, at only a 12 percent increase in price".[8] The improvement in Price–performance of the 303X models created volume of orders sufficient to cause a backlog. "The backlog backfired. IBM inadvertently gave Amdahl a huge boost when the results of its "delivery lottery" pushed some customer shipments all the way into 1980".[9]

In October, 1977 Computerworld reported that Itel's "air-cooled AS/6" was announced "within six hours of the IBM announcement" and due to ship "the same time deliveries of the IBM 3032 are slated to begin."[10]

Magnuson Computer Systems also produced the M80 System/370-compatible computer system between 1975 and 1980.[11]

IBM 3031

The 3031 features a machine cycle time of 115 nanoseconds (ns). It has a cache (called "high speed buffer storage" in IBM terminology) size of 32 KB. Main storage may be 2 to 6 MB, in 1 MB increments. One group of six channels is standard. This group of channels contains one byte multiplexer and five block multiplexer channels. An optional channel-to-channel adapter (CTCA) is available. At announcement the monthly lease price for a minimally configured 3031 processor (2 MB, without peripherals) was $27,497. The 3031 is supported by MVS, OS/VS1 SVS, VM/370, ACP, and TSS/370, and DOS/VS, the last of which is not mentioned as supported by the other 303X models.[2]

Models

The 3031 has 15 models, distinguished by the amount of main storage installed.[4]

IBM 3032

The 3032 features a machine cycle time of 80 ns. It has a cache size of 32 KB. Main storage may be 2, 4, or 6 MB. One group of six channels is standard; this can optionally be expanded by the addition of another six. Each group of channels contains one byte multiplexer and five block multiplexer channels. Later on, the optional feature Data Streaming was added; it allowed the first block multiplexer channel in each Director to operate at 3 MB per second. An optional channel-to-channel adapter (CTCA) is available. At announcement the monthly lease price for a minimally configured 3032 processor (without peripherals) was $43,740. The 3032 is supported by MVS, OS/VS1 SVS, VM/370, ACP, and TSS/370.[3]

Models

The 3032 has 4 models, distinguished by the amount of main storage installed.[4]

IBM 3033

The 3033 features a machine cycle time of 58 ns. It has a cache size of 64 KB. Initially the main storage was 4, 6, or 8 MB, later on this was expanded on some of the models to 8, 12 or 16 MB. Two groups of six channels are standard; this can optionally be expanded by the addition of another four (in 370 mode a system has max 16 channels). Each group of channels contains one byte multiplexer and five block multiplexer channels. An optional channel group is available consisting of either four block multiplexer channels or one byte multiplexer and three block multiplexers. Later on, the optional feature Data Streaming was added; it allowed the first block multiplexer channel in each Director to operate at 3 MB per second. Two optional channel-to-channel adapters (CTCA) are available. At announcement the monthly lease price for a minimally configured 3033 processor (without peripherals) was $70,400. The 3033 is supported by MVS, OS/VS1 SVS, VM/370, and ACP.[12]

The 3033-N, a slightly slower model, was introduced Nov. 1, 1979, and the 3033-S, with about 2/3 the speed of the original 3033 model, was introduced a year later, on November 12, 1980. The 3033-S was only equipped with one Channel Director, and the main storage was simplified and did not run in 4-way interleave mode. Each shipped the following quarter; both were withdrawn in 1985, along with the other 303X offerings.[13]

The 3033 was later made available in attached-processor (AP) and multiprocessor (MP) dyadic configurations.

The 3033 AP configuration consisted of one 3033 and one 3042 interconnected. The first version of the 3042 did not have any channels, so all I/O operations had to be done from the 3033; the 3042 provided additional cpu power. Later versions (3042-2) did have one or two Channel Directors, thus enabling I/O operations. This also allowed the system to be partitioned into two parts, where one part could be temporarily down, for example, for maintenance, while still allowing the other part to continue to run.

The 3033 MP configuration consisted of two 3033 interconnected. Similar to the later 3033 AP, they could be partitioned into two parts, in example for running maintenance on one processor at a time. All 3033 AP and MP configurations includes two 3036 consoles.

Models

The 3033 had 29 models.[4][14]

Photos
  • IBM 3031
  • IBM 3032 Archived 2017-01-31 at the Wayback Machine
  • IBM 3032; note IBM 3036 Dual-display console, partial view of Univac 1108 on right side
  • "IBM 3033 with users". IBM. Retrieved 4 June 2023.

See also

Notes
  1. IBM used a capital X when referring to 303X, as did print media; see Computerworld ref below.
  2. Google has several listings for "MVS/System Extensions" (plural), and none for the singular form
  3. or a similar reference, "S/370 3033-U" used by IBM at ftp://public.dhe.ibm.com/software/mktsupport/techdocs/allreal.pdf

References
  1. "IBM announces new processor for large system users". IBM History Archives. IBM. 23 January 2003.
  2. "3031 Processor Complex". IBM Archives. IBM. 23 January 2003.
  3. "3032 Processor Complex". IBM Archives. IBM. 23 January 2003. Retrieved Feb 8, 2018.
  4. "Mainframe - Family tree and chronology 2". IBM Archives. IBM. 23 January 2003.
  5. "Two 370-Compatible Systems Unveiled by California Group". Computerworld. October 23, 1978. p. 41.
  6. Gerard O’Regan (2013). Giants of Computing: A Compendium of Select, Pivotal Pioneers. Springer. ISBN 978-1447153405. IBM's machines were water-cooled, while Amdahl's were air-cooled
  7. "ES/9000 Characteristics". IBM Archives. IBM. 23 January 2003.
  8. Campbell-Kelly, artin (Jun 8, 2015). From Mainframes to Smartphones. Harvard University Press. ISBN 978-0-674-28655-9. Retrieved Feb 9, 2018.
  9. Von Simson, Ernest (2010). The Limits of Strategy: Lessons in Leadership from the Computer Industry. iUniverse. p. 55. ISBN 978-1-4401-9259-3.
  10. "New IBM Processors Flush Out Itel AS/6, But Amdahl Stands Pat". Computerworld. October 17, 1977. p. 1.
  11. Magnuson M80 Models 30, 31, 32, 42 and 43 Computer Systems. Retrieved Feb 9, 2018. {{cite book}}: |website= ignored (help)
  12. IBM Corporation (23 January 2003). "3033 Technical press release". IBM Archives. Retrieved Feb 9, 2018.
  13. "IBM Mainframes – 45+ Years of Evolution" (PDF). p. 25.
  14. "3033 Chronology". IBM Archive. IBM. 23 January 2003.

Further reading
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