Mcm

6947ch02.fm

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

Book 3

Book 0

Book 1

Book 2

Figure 2-4 Concentric ring structure

A memory-coherent director optimizes ring traffic and filters out cache traffic by not looking on the ring for cache hits in other books if it is certain that the resources for a given logical partition exist in the same book.

The Level 2 (L2) cache is implemented on four cache (SD) chips. Each SD chip holds 8 MB, resulting in a 32 MB L2 cache per book. The L2 cache is shared by all PUs in the book and has a store-in buffer design. The connection to processor memory is done through four high-speed memory buses.

There is a ring structure within which the books maintain interbook communication at the L2 cache level. Additional books extend the function of the ring structure for interbook communication. The ring topology is shown in Figure 2-5and Figure 2-6 on page 31, and in Figure 2-7 on page 31.

A book jumper completes the ring in order to be able to insert additional books into the ring non-disruptively.

		MBA Card
4 x 2 GB/S		4 x 2 GB/S		4 x 2 GB/S
STI	STI	STI	STI	STI	STI
STI	STI	STI	STI	STI	STI
MBA		MBA		MBA
	Memory Up to 64GB										Jumper Book
		MCM
Level 2 Cache 32MB
PU	PU PU PU PU PU		PU PU PU	PU PU	PU
						Ring Structure
						PU PU PU PU PU PU PU PU PU PU PU PU
						Level 2 Cache 32MB
Jumper Book								MCM
Jumper Book						Memory Up to 64GB
						Memory Up to 64GB
						MBA		MBA		MBA
						STI	STI	STI	STI	STI	STI
		Level 2 Cache 32MB				STI	STI	STI	STI	STI	STI
		Level 2 Cache 32MB				4 x 2.5 GB/S		4 x 2.5 GB/S		4 x 2.5 GB/S

Figure 2-5 Two-book system ring structure

30IBM eServer zSeries 990 Technical Guide

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.

IBM 990 manual Mcm

Models: 990

Figure 2-4 Concentric ring structure

Figure 2-5 Two-book system ring structure

990 specifications