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IBM 308X

The IBM 308X is a line of mainframe computers that implemented the IBM System/370 architecture and, starting in 1983, the System/370 Extended Architecture, which extended the original 24-bit addressing to 31-bits, thereby allowing programs to access much larger sets of data. S/370-XA was used in the new MVS/SP V2 operating system and the Start Interpretive Execution (SIE) instruction used by the new Virtual Machine/eXtended Architecture Migration Aid.

{{anchor}}IBM 3081
The initial 3081 offered, the 3081D, was a 5 MIPS machine. The next offering, the 3081K, was a 7 MIPS machine. Last came the 3081G, again a 5 MIPS machine. The 3081D was announced Nov 12, 1980; the 3081K came nearly a year later; the 3081G was introduced September 3, 1982 as part of the initial 3084 announcement. The dyadic concept offers "under the cover" dual processors. All models of 3081 and 3083 had the same size, components and footprint; the CPU itself (3081 or 3083), the service processor that also contained the channels (3082), and the water pump/coolant unit (3087). The 308X Processor Complex was using 400 Hz power, this could be supplied by either an optional motor/generator unit (3089), or it could be supplied by an external power source. 3081 as successor to 3033 Some key technological features of the 3081, compared to the previous most powerful processor, the 3033, were the following: • About 800,000 circuits implemented in large scale integration, using up to 704 logic circuits per chip, which provided the required performance, reliability, and serviceability that were design goals • "Elimination of one complete level of packaging, the card level" Both central processors have access to channels (as many as 24), and main memory (up to 32 megabytes). ==IBM 3083==
{{anchor}}IBM 3083
The IBM 3083 was described by an IBMer as "never intended to be built," ==IBM 3084==
{{anchor}}IBM 3084
Announced September 3, 1982 and withdrawn August 4, 1987. While all 3081/3083 shared the same physical footprint, the 3084 system doubled this setup, the CPU was double in length, two 3082, and two 3087 was used. For systems using the optional 3089, two units were required. The 3084 could run in two different modes. When running in PP-mode (Partial Processing), it was configured as two independent systems. The other mode was called SI-mode (Single Image), then all four processors were running as one system. ==See also==
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