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

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change the PU characterization of the server they are upgrading. In addition, customers who are consolidating may not be increasing total capacity, and/or they may wish to take advantage of the multiple Logical Channel Subsystems offered. z990-to-z990 model upgrades and feature adds may be completed concurrently.

Model downgrades

There are no model downgrades offered. Customers may purchase unassigned CPs or IFLs for future use. This avoids the placement of RPQ orders and subsequent sequential MES activity, and paying software charges for capacity that is not in use.

Concurrent Processor Unit (PU) conversions

z990 servers support concurrent conversion between different PU types, providing flexibility to meet changing business environments. Assigned CPs, unassigned CPs, assigned IFLs, unassigned IFLs, and ICFs may be converted to assigned CPs, assigned IFLs or ICFs, or to unassigned CPs or unassigned IFLs.

1.3 System functions and features

The 990 system offers the following functions and features.

1.3.1 Processor

IBM introduced the Processor Resource/Systems Manager™ (PR/SM) feature in February 1988, supporting a maximum of four logical partitions. In June 1992, IBM introduced support for a maximum of 10 logical partitions and announced the Multiple Image Facility (MIF, also known as EMIF), which allowed sharing of ESCON channels across logical partitions—and since that time has allowed sharing of more channels across logical partitions (such as Coupling Links, FICON and OSA). In June 1997, IBM announced increased support - up to 15 logical partitions on Generation 3 and Generation 4 servers.

The evolution continues and IBM is announcing support for 30 logical partitions. This support is exclusive to z990 and z890 models.

MCM technology

The z990 12-PU MCM is smaller and more capable than the z900’s 20-PU MCM. It has 16 chips, compared to 35 for the z900. The total number of transistors is over 3 billion, compared with approximately 2.5 billion for the z900. With this amazing technology integration comes improvements in chip-to-substrate and substrate-to-board connections.

The z990 module uses a connection technology, LAN Grid Arrays (LGA), pioneered by the pSeries™ in the p690 and the i890. LGA technology enables the z990 substrate, with only 53% of the surface area of the z900 20 PU MCM substrate, to have 23% more I/Os from the logic package.

Both the z900 and z990 have 101 layers in the glass ceramic substrate. The z990's substrate is thinner, shortening the paths that signals must travel to reach their destination (another chip or exiting the MCM). Inside the low dielectric glass ceramic substrate is 0.4 km of internal wiring that interconnects the 16 chips that are mounted on the top layer of the MCM. The internal wiring provides power and signal paths into and out of the MCM.

The MCM on the z990 offers flexibility in enabling spare PUs via the Licensed Internal Code Configuration Control (LIC-CC) to be used for a number of different functions. These are:

￿A Central Processor (CP)

Chapter 1. IBM zSeries 990 overview 5

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IBM 990 System functions and features, Model downgrades, Concurrent Processor Unit PU conversions, MCM technology
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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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