Background History Note 1 Refer to Soltis: Appendix

Many many years ago Over 20 years ago when the S/38 was being developed, the world had never heard of Microsoft or Netscape. The IBM Corporation had experienced the loss of hardware sales to “look alike” vendors Amdahl and others. On the large mainframe front, IBM had just canceled a project known as FS (Future Systems) that was going be a revolutionary replacement for the existing line of IBM mainframe computers.

The Rochester Group Mid-1960s  At Rochester, Minnesota, a realization that a large market existed for a small, special purpose business computer. IBM did not share this vision (System/360 was just announced). “The group at Rochester didn’t bother to tell the Corporation they were building a new computer. Instead, they declared they were building a new unit-record machine”. Frank Soltis, Chief architect of the AS/400. The System/3 was born in 1969  Using RPG (a non-procedural language) Enhanced to System/32 (1975), System/34 (1977), System/36 (1983) System/38 (1978)  a new concept and architecture The AS/400 announced in June 1988.

Why the AS/400 Businesses typically decide on the application software first, then choose a computer to run it on. The AS/400 has over 25,000 business applications worldwide The AS/400 is designed and built as a total system, fully integrating all the hardware and software components that a business needs. The AS/400 is a unique system that is defined by software not by hardware. Instructions have to pass through a layer of microcode before they can be understood by the hardware itself. When a different hardware technology is to be deployed, IBM rewrites sections of the microcode to absorb the changes in hardware characteristics, so that the interface presented to the customer remains the same.

A fully integrated system. It’s all in there ! All the software components : the Operating System, a relational database, software for comprehensive security, communications subsystems, and Internet capabilities are already there. On an ordinary machine these software modules are provided by third parties. All the components are designed to work together seamlessly. And are fully tested as a whole system. Easier to install, maintain, and use  Lower operational costs for a business

A Layered Architecture User Applications Layer OS/400 System Layer MI Microcode Layer Hardware Layer The MI layer ensures that all components are fully integrated. You can not by-pass the MI layer

AS/400 System Concepts and Architecture The AS/400 and the S/38 share the same architectural base : “Capability-based” addressing and Single-level Storage Capability is a pointer to an object in the computer system

The MI interface Rather than having the instruction set of the computer being designed by the engineers, the programmers (the real users of the system) were defining an instruction set for an abstract machine. These instructions rather than be optomized for the hardware were being designed for writing software applications. This abstract machine interface would eventually become known as MI (Machine Interface) or what IBM currently calls TIMI (technology Independent Machine Interface). This abstract Machine Interface (MI) defined some very advanced concepts to make programming more efficient and less error prone.

The MI interface Programmers would write programs for an abstract machine using new concepts like not loading data into a hardware registers for processing. In this new abstract machine programmers would improve the reliability of programs by prevented programs from modifying storage to manipulate address registers. Using MI programs could manipulate pointers but the abstract machine would not allow a change that would cause a pointed to be corrupted. This abstract machine interface was being designed to protect programmers from themselves. On previous hardware the programmers knew the addressing structure of pointers and could even alter memory to change the address (which often was the cause of program reliability problems).

The iSeries Operating System [OS/400] The operating system provides the tools that a user will use to run the AS/400 system The major functions of the OS/400 program are: 1.Control Language Control language is the set of commands used to talk with the computer. 2.Data Management Data management allows the user to define and use data files. 3.Work Management Work management controls many jobs, no matter if you are doing several at the same time, or if other people are using the system. 4.Programmer Services Programmer services provide support for online program development and testing. –System Operator Services System operator services provide a menu for easy access to frequently used operator functions.

Cont. 6. Communication Support The OS/400 program supports a wide range of communication functions that allow your AS/400 system to communicate with other types of systems as well as other AS/400 systems. 7. Security Security protects your valuable work. 8. PC Support The PC Support program provides a means of attaching your personal computer to your AS/400 system as a programmable workstation And many more !!!

Work Management 7. Work Management There are two types of processing: ° Interactive processing, which requires continuous interaction between the user and the computer. ° Batch processing, which frees the user and the display station to do other things once the job has been submitted. Characteristics of batch jobs: ° Don't need a user (other than to submit a job) ° Don't use display stations (other than to request the job) ° Are always started from a job queue

The Applications Layer How does the system user or applications developer interface with the OS/400 on a command level  Control Language (CL) CL is a set of OS/400 Commands that control system configuration, system operation, programming, object management, process management, and security. Has a simple structure: Verb-Object form (a dozen verbs): Each control language command has the same structure, made up of two parts: ° Command name ° Parameters

Why the iSeries iSeries addresses business and infrastructure needs è Addresses today's IT needs è Establishes the building blocks for e-business on demand

From Traditional to New Economy New Economy  dominant platforms used by companies are Solaris, Linux, and Windows 2000/XP. Traditional brick-and-mortar companies  the AS/400 is still a major platform. –need something that's capable of handling heavy transactions.

IBM Series computers