6947ch02.fm

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

z990

Image

Definable Central Storage (CS)

Mode

Modes

and Expanded Storage

ESA/390 Mode

 

CS < = 128 GB

 

CPs

ES = Yes

CPs and zAAPs

 

 

ESA/390 TPF Mode

 

CPs only

Logically

 

Partitioned

Coupling Facility Mode

Mode

ICFs and/or CPs

 

Linux Only Mode

 

IFLs or CPs

CS < = 128 GB ES = Yes

CS < = 128 GB ES = No

CS < = 128 GB ES = Yes

Figure 2-18 Modes and memory diagram

Table 2-9 shows the z990 storage allocation and usage possibilities, which depend upon the image and architecture modes.

Table 2-9 Storage definition and usage possibilities

Image mode

Architecture mode

Maximum central storage

Expanded storage

 

(addressability)

 

 

 

 

 

Architecture

z990

z990

Operating

 

 

 

 

 

definition

definable

system usage

 

 

 

 

 

 

ESA/390

z/Architecture (64-bit)

16 EB

128 GB

yes

only by z/VM

 

 

 

 

 

 

 

ESA/390 (31-bit)

2 GB

128 GB

yes

yes

 

 

 

 

 

 

ESA/390 TPF

ESA/390 (31-bit)

2 GB

128 GB

yes

yes

 

 

 

 

 

 

Coupling Facility

CFCC (64-bit)

16 EB

128 GB

no

no

 

 

 

 

 

 

Linux Only

z/Architecture (64-bit)

16 EB

128 GB

yes

only by z/VM

 

 

 

 

 

 

 

ESA/390 (31-bit)

2 GB

128 GB

yes

yes

 

 

 

 

 

 

Remember that either a z/Architecture mode or an ESA/390 architecture mode operating system can run in an ESA/390 image mode on a z990. Any ESA/390 image can be defined with more than 2 GB of central storage and can have expanded storage. These options allow you to configure more storage resources than the operating system is capable of addressing.

ESA/390 mode

In ESA/390 mode, storage addressing can be 31 or 64 bits, depending on the operating system architecture and the operating system configuration.

An ESA/390 mode image is always initiated in 31-bit addressing mode. During its initialization, a z/Architecture operating system can change it to 64-bit addressing mode and operate in the z/Architecture mode.

68IBM eServer zSeries 990 Technical Guide

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Page 82
Image 82
IBM 990 manual ESA/390 mode, Operating, Definition Definable
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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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