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

6947ch04.fm

We suggest you establish a naming convention for the logical partition identifiers. As shown in Figure 4-2,you could use the LCSS number concatenated to the MIF Image ID, which means logical partition ID 3A is in LCSS 3 with MIF ID A. This fits within the allowed range of logical partition IDs and conveys useful information to the user.

Dynamic Addition or Deletion of a logical partition name

In order to have a partition defined for future use, such a dynamic partition must be reserved beforehand in the IOCDS that is used for Power-On Reset. A reserved partition is defined with a partition name placeholder, a MIF ID, a usage type, and optionally may contain a description. The reserved partition can be assigned a logical partition name later to be used in I/O commands of HCD.

Important: Some HCD and HCM panels may still refer the user to the definition of a “logical partition number”. For a z990 configuration, this is incorrect and the user should understand that the panel refers to the definition of a “MIF id”

As previously mentioned, on a z990 the “logical partition number” is assigned by PR/SM during Power-on Reset and cannot be modified, nor visualized, by the user.

4.1.2 Physical Channel ID (PCHID)

A Physical Channel ID, or PCHID, reflects the physical identifier of a channel-type interface. A PCHID number is based on the I/O cage location, the channel feature slot number, and the port number of the channel feature. A CHPID does not directly correspond to a hardware channel port on a z990, and may be arbitrarily assigned. A hardware channel is now identified by a PCHID, or Physical Channel Identifier.

You can address 256 CHPIDs within a single Logical Channel Subsystem. That gives a maximum of 1024 CHPIDs when four LCSSs are defined. Each CHPID is associated with a single channel. The physical channel, which, uniquely identifies a connector jack on a channel feature, is known by its PCHID number.

PCHIDs identify the physical ports on cards located in I/O cages and follow the following numbering scheme:

Cage

Front PCHID ##

Rear PCHID ##

 

 

 

 

I/O Cage 1

100

- 1FF

200 - 2BF

 

 

 

 

I/O Cage 2

300

- 3FF

400 - 4BF

 

 

 

 

I/O Cage 3

500

- 5FF

600 - 6BF

 

 

 

 

CEC Cage

000

- 0FF reserved for ICB-4s

 

 

 

 

CHPIDs are not pre-assigned. It is the responsibility of the user to assign the CHPID numbers through the use of the CHPID Mapping Tool (CMT) or HCD/IOCP. Assigning CHPIDs means that the CHPID number is associated with a physical channel port location (PCHID), and a LCSS. The CHPID number range is still from ‘00’ to ‘FF’ and must be unique within an LCSS. Any CHPID not connected to a PCHIDs will fail validation when an attempt is made to build a production IODF or an IOCDS.

A pictorial view of a z990 with multiple LCSS is shown in Figure 4-3. Two Logical Channel Subsystems are defined (LCSS0 & LCSS1). Each LCSS has three logical partitions with their associated MIF Image Identifiers.

Chapter 4. Channel Subsystem 113

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IBM 990 manual Physical Channel ID Pchid, Dynamic Addition or Deletion of a logical partition name
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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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