6947ch07.fm

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

A function is introduced with the z990 server, implemented in the server's Support Element code, which now requires the ETR Network ID of the attached Sysplex Timer Network to be manually set in the Support Element at installation time. This function checks that the ETR Network ID being received in the timing signals via each of the server's two ETR ports matches the ETR Network ID manually set in the server's Support Element (SE).

Up to two Sysplex Timer units can be configured in an Expanded Availability configuration, each one with a unique ETR ID. When in Expanded Availability configuration, a network ID (Net ID) is also assigned at installation time to identify that these two Sysplex Timer units belong to the same Sysplex Timer configuration.

The z990 requires that the ETR Network ID of the attached Sysplex Timers be entered in a panel on the Support Element (SE). As part of the installation of a Sysplex Timer in either Basic or Expanded Availability configuration, each IBM 9037 Sysplex Timer Unit is assigned an ETR Network ID (0 to 31 decimal) and an ETR Unit ID (0 to 31 decimal). Within the valid range, the ETR Network ID and ETR Unit ID values are arbitrary and can be chosen by the customer to uniquely identify an ETR network and a unique ETR unit (Sysplex Timer) within the ETR network.

In addition, on the same panel, the ETR ports have to be enabled for stepping the TOD. This function checks that the ETR Network ID being received in the timing signals via each of the two ETR ports matches the ETR Network ID manually set in the z990 Support Element. This provides greater checking, helping eliminate cabling errors where a z990 ETR port may be incorrectly connected to a Sysplex Timer Unit in an incorrect Sysplex Timer ETR network, and allows verification of cabling connectivity from the Sysplex Timer to the z990 server prior to IPLing z/OS or OS/390.

To get the appropriate SE panel, log on to the SE directly or via the HMC single object operations task. Navigate to the CPC Configuration task list and invoke the System Complex (Sysplex) Timer task. Once this task is invoked, a notebook is displayed with two panels. The first panel contains configuration information, as shown in Figure 7-2;the ETR Network ID (0-31) is entered on this configuration panel.

158IBM eServer zSeries 990 Technical Guide

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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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