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

6947ch02.fm

availability purposes. Reports from the CHPID Mapping tool can help you validate your I/O configuration.

Book upgrades with substantial additions of I/O cards may require the additional STIs to be used. In that case it is good practice to consider rebalancing the STI configuration (FC 2400). More information about I/O balancing, see “Balancing I/O connections” on page 79. Be aware that rebalancing of the STI configuration as a result of the addition of one or more books is disruptive.

Book replacement and connectivity

When a book must be replaced, for example due to an unlikely MCM failure, the MBA/STIs connectors from the failing book are unavailable. Until the failing book is replaced, Power-On Reset of the CPC with the remaining books is not supported.

2.1.6 Frames and cages

The z990 frames are enclosures built to Electronic Industry Association (EIA) standards. The z990 server always has two frames that are composed of two 40 EIA frames. The A and Z frames are bolted together and have two cage positions (top and bottom).

￿Frame A has the CEC cage at the top and I/O cage 1 at the bottom.

￿Frame Z can be one of the following configurations:

–Without I/O cage.

–With one I/O cage (I/O cage 2 at the bottom).

–With two I/O cages (I/O cage 2 at the bottom and I/O cage 3 on top).

All books, the DCAs for the books, and the cooling components are located in the CEC cage in the top half of the A-frame of the z990. In Figure 2-9 on page 33 the arrows point to the front view of the CEC cage in which four books are shown as being installed.

.

 

 

 

Z frame

 

A frame

 

IBF

 

IBF

 

IBF

 

MRU

MRU

BPD

 

 

 

I/OCage 3

 

 

CEC Cage

MDA

MDA

MDA

MDA

I/OCage 2

 

 

I/O Cage 1

MDA

MDA

MDA

MDA

Figure 2-9 CEC cage and I/O cage locations

Chapter 2. System structure and design 33

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IBM 990 manual Frames and cages, Book replacement and connectivity
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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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