The IBM 303XIBM used a capital X when referring to 303X, as did print media; see Computerworld ref below. 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. Two additional processors, the 3031 and the 3032, were announced on October 6, 1977. All three 303X systems were withdrawn on February 5, 1985.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 memory, 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 IBM System/370, System/370 with an equal amount of computer memory and an identical number of Channel I/O, channels because "the channels are physically integrated within the processor mainframe." Each group of six channels has its own Microprogramming, microprogrammed channel processor, a System/370-158-type processor running special channel microcode. The initial announcement of the 3033 also introduced new operating system versions "MVS/System ExtensionsGoogle has several listings for "MVS/System Extensions" (plural), and none for the singular form (MVS#MVS/SE, MVS/SE) and VM (operating system), VM/System Extensions (VM/SE)."

303X as successor to IBM System/370, System 370

Beginning in 1977, IBM began to introduce new systems, using the following descriptions: * "A compatible member of the System/370 family." * "System/370 Compatible - 303(1/2/3)" * "the System/370 3033 Processor."or a similar reference, "S/370 3033-U" used by IBM at ftp://public.dhe.ibm.com/software/mktsupport/techdocs/allreal.pdf

Competing compatibles

At this time, other companies, known as plug compatible manufacturers (PCMs), were competing with IBM by producing IBM-compatible systems. By the late 1970s and early 1980s, patented technology allowed Amdahl Corporation, Amdahl IBM-compatible mainframes of this era to be completely air-cooled, unlike IBM systems that required chilled water and its supporting infrastructure— the 8 largest of the 18 models of the ES/9000 systems introduced in 1990 were water-cooled; the other ten were air-cooled. "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". The improvement in Price–performance ratio, 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". In October, 1977 Computerworld reported that Hitachi Data Systems#Origins as Itel, 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." Magnuson Computer Systems also produced the M80 System/370-compatible computer system between 1975 and 1980.

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, IBM Airline Control Program, ACP, and TSS (operating system), TSS/370, and DOS/VS, the last of which is not mentioned as supported by the other 303X models.

Models

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

IBM 3032

The 3032 features a machine cycle time of 80ns. 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. An optional feature allows the first block multiplexer in each group 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, IBM Airline Control Program, ACP, and TSS (operating system), TSS/370.

Models

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

IBM 3033

The 3033 features a machine cycle time of 58ns. It has a cache size of 64 KB. Main storage may be 4, 6, or 8 MB. Two groups of six channels are 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. An optional channel group is available consisting of either four block multiplexer channels or one byte multiplexer and three block multiplexers. An optional feature allows the first block multiplexer in each group 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 IBM Airline Control Program, ACP. 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. Each shipped the following quarter; both were withdrawn in 1985, along with the other 303X offerings. The 3033 was later made available in Asymmetric multiprocessing, attached-processor (AP) and Multiprocessing, multiprocessor (MP) dyadic configurations.

Models

The 3033 had 29 models.

Photos

IBM 3031

IBM 3032

IBM 3032; note IBM 3036 Dual-display console, partial view of Univac 1108 on right side

IBM 3033

Features

303X as successor to IBM System/370, System 370

Competing compatibles

IBM 3031

Models

IBM 3032

Models

IBM 3033

Models

Photos

See also

Notes

References

Further reading