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

6947ch03.fm

 

 

 

 

 

Domain

I/O slots in domain

 

 

 

 

 

 

5

20, 22, 25, 27

 

 

 

 

 

 

6

29, 30, 31, 32

 

 

 

 

 

Each eSTI-M card is connected to an STI jack located in a book’s Memory Bus Adapter (MBA) via an STI cable. As each eSTI-M card requires one STI, up to seven STIs are required to support one I/O cage. A fully populated three-I/O cage system requires 21 STIs.

IBM selects which slots are used for I/O cards and supplies the appropriate number of I/O cages and STI cables, either for a new build server or for an existing server upgrade.

Important: Installing an additional I/O cage to an existing z990 server configuration is disruptive. The Plan Ahead process allows you to avoid this outage by including, in the initial z990 server order, the number of optional I/O cages required by a future I/O configuration.

3.2.1 Self-Timed Interconnect (STI)

There are three Memory Bus Adapters (MBAs) on each z990 book. Each MBA has four Self-Timed Interconnects (STIs), resulting in a total of 12 STIs on each z990 book. Each STI has a bandwidth of 2 GB/sec full-duplex, resulting in a maximum bandwidth of 24 GB/sec per z990 book.

Depending on the number of books in the configuration, there will be 12, 24, 36 or 48 STIs in a z990 server, as shown in Table 3-2.

Table 3-2 Number of MBAs and STIs

z990 Model

Number of books

Number of MBAs

Number of STIs

 

 

 

 

2084-A08

1

3

12

 

 

 

 

2084-B16

2

6

24

 

 

 

 

2084-C24

3

9

36

 

 

 

 

2084-D32

4

12

48

 

 

 

 

The z990 model D32 has a maximum bandwidth of 96 GB/sec.

3.2.2 STIs and I/O cage connections

Figure 3-3 on page 78 shows the STI connections from the server’s CEC cage to an I/O cage, and to an Integrated Cluster Bus-4 (ICB-4) link.

Chapter 3. I/O system structure

77

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IBM manual STIs and I/O cage connections, Z990 Model Number of books Number of MBAs Number of STIs
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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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