Draft Document for Review April 7, 2004 6:15 pm

6947ch06.fm

z990 Compatibility for selected OS/390, and z/OS releases

OS/390 V2.10, z/OS V1.2, and z/OS V1.3 require the Web delivered Compatibility support to run on a z990.

Attention: Compatibility nor Exploitation support is not available for z/OS 1.1

Compatibility support allows these releases to:

￿Define a z990 environment with HCD

￿Run on a z990 processor in a logical partition in LCSS-0, using an LPAR id equal to or less than x’F’.

￿Coexist in a sysplex that contains a z990 processor

￿Coexist with z990 processors sharing disk devices outside of a sysplex.

Compatibility support requirements

Compatibility support is required under the following circumstances.

￿Compatibility support is required for all images running on a z990.

￿Compatibility support is required on any image that is used for defining the I/O configuration for the z990.

￿Compatibility support is required on all images in a sysplex, whether running on a z990 or not, if a Coupling Facility logical partition for that sysplex is running on a z990 and has an LPAR identifier greater than 15 ( x’F’).

Compatibility support allows the supported operating systems to run in LCSS 0 on the z990 processor. It is not possible to run z/OS or OS/390 in LCSSs 1, 2, and 3, even with the compatibility maintenance. This is supported on z/OS 1.4 with the exploitation support and subsequent releases.

Note: A Coupling Facility logical partition can reside in any Logical Channel Subsystem

Compatibility support can run on any processor that is already supported by one of the listed operating systems. For example, you can install Compatibility support on a z/OS V1.2 system that is running on a IBM 9672 G5 processor.

Figure 6-1 shows a situation where the Compatibility support is not required for systems not on the z990.

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IBM manual Z990 Compatibility for selected OS/390, and z/OS releases, Compatibility support requirements
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990 specifications

The IBM 990 series, often referred to in the context of IBM's pioneering efforts in the realm of mainframe computing, represents a unique chapter in the history of information technology. Introduced in the late 1960s, the IBM 990 series was designed as a powerful tool for enterprise-level data processing and scientific calculations, showcasing the company's commitment to advancing computing capabilities.

One of the main features of the IBM 990 was its architecture, which was built to support a wide range of applications, from business processing to complex scientific computations. The system employed a 32-bit word length, which was advanced for its time, allowing for more flexible and efficient data handling. CPUs in the IBM 990 series supported multiple instructions per cycle, which contributed significantly to the overall efficiency and processing power of the machines.

The technology behind the IBM 990 was also notable for its use of solid-state technology. This provided a shift away from vacuum tube systems that were prevalent in earlier computing systems, enhancing the reliability and longevity of the hardware. The IBM 990 series utilized core memory, which was faster and more reliable than the magnetic drum memory systems that had been standard up to that point.

Another defining characteristic of the IBM 990 was its extensibility. Organizations could configure the machine to suit their specific needs by adding memory, storage, and peripheral devices as required. This modular approach facilitated the growth of systems alongside the technological and operational demands of the business environments they served.

In terms of software, the IBM 990 series was compatible with a variety of operating systems and programming environments, including FORTRAN and COBOL, enabling users to access a broader array of applications. This versatility was a significant advantage, making the IBM 990 an appealing choice for educational institutions, research facilities, and enterprises alike.

Moreover, the IBM 990 was engineered to support multiprocessing, which allowed multiple processes to run simultaneously, further increasing its effectiveness in tackling complex computing tasks.

In summary, the IBM 990 series represents a significant advancement in computing technology during the late 20th century. With a robust architecture, versatile configuration options, and a focus on solid-state technology, the IBM 990 facilitated substantial improvements in data processing capabilities, making it a cornerstone for many businesses and academic institutions of its time. Its impact can still be seen today in the continued evolution of mainframe computing.
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