Preface

The Application System/400'" (AS/400'") is IBM's newgeneration of midrange computers. Incorporatingmany characteristics of the System/So and Sys-tem/38, the AS/400 has more power and capabilitythan those predecessors. In this issue, the first sixpapers provide technical information on the designand structure of the AS/400 and show how IBM Busi-ness Partners and the user community performed avital role in its development. We are indebted toG. R. Falkowski and M. E. Gauthier of IBM Appli-cation Business Systems in Rochester, Minnesota,for their contributions to the inception and forma-tion of these six articles.

In the first paper of the group on the AS/400,Schleicher and Taylor present a description of thesystem from the design viewpoint. They describe themotivation for the system, the requirements andother factors bearing on its design, and the ap-proaches used to implement the design. Among thecharacteristics of the implementation are a layeredarchitecture, object orientation, distributed process-ing, and independence of programs, data, and sys-tems. In the last part of the paper, the authors brieflydescribe some of the system facilities.

During the origination of the AS/400, IBM BusinessPartners, systems engineers, industry specialists, cus-tomers, and IBM marketing personnel were involvedin developing and testing this new system and increating and migrating applications for it. The newoperating system, OS/400'", incorporates the systemfunctions of the IBM System/So and System/38 andimplements the principles of Systems ApplicationArchitecture (SAA). This approach permits supportfor the billions of lines of application code that hasalready been developed by industry and providesAS/400 interconnection with System/36, System/38,the IBM Personal System models, and Systems Net-work Architecture LV 6.2. Pine discusses two of theinnovative processes through which this ambitiousplan was carried out: early user involvement andmigration invitationals.

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Feedback from the early user involvement processinto the development of the AS/400 meant that earlyuser experiences could serve to enhance the designand development of the hardware and software dur-ing their formative stages. Sulack, Lindner, and Dietzdiscuss the organizational dynamics of this new op-erational procedure. An iterative process for design,production, testing, and user verification was inte-grated with the market analysis and verification pro-grams previously discussed by Pine. Together, theseelements coalesced into a process breakthroughwhich ensured that the aggressive goals set for theAS/400 were achieved.

Certain positive features of the AS/400 architectureand certain beneficial functions of the OS/400 werenot introduced in earlier systems because they hadbeen accompanied by poor system performance.Clark and Corrigan discuss design and optimizationtechniques used in the AS/400 that allow the systemto offer excellent price and performance character-istics, along with the benefits of those new capabili-ties.

One of the key features of the AS/400 is its consistent,easy-to-use interface. The Charland paper delves intothe help facility, a very important aspect of the userinterface and vital to its acceptability. The essentialdesign concept of the AS/400 help facility is the infor-mation module. Help is provided in chunks of in-formation beginning at the current position of thecursor, and further help can be requested by the userin chunks of increasing depth and specificity. Theauthor discusses the extensive testing process used tovalidate this new help facility. The structure of thehelp facility is derived from the SAA Common UserAccess (eVA). As required by eVA, contextual helpand a help index are provided. A significant addi-tional feature gives users a word-oriented searchcapability.

The primary focus of the last paper in the group onthe AS/400, by Botterill, is a discussion ofthe rationaleand design approach for the user interface-an in-terface intended to address the needs of a broad

IBM SYSTEMS JOURNAL, VOL 28, NO 3, 1989

spectrum of users. The ASj400 system interface isprimarily a nonprogrammable terminal interfacethat is based on advances in object-oriented interfacedesign and is simple to use and understand. It is alsoconsistent across all ASj400 functions and successfullyintroduces consistency between programmableworkstations and nonprogrammable terminals.

In a different but supportive vein, Ten Dyke andKunz provide an introduction and overview on thesubject of object-oriented programming. This styleof programming was used for the software structureof the ASj400. In the paper, emphasis is placed onsetting the subject in perspective among the manyother techniques for programming and within thehistory of techniques that lead to the current interestin the object-oriented approach. The authors useexamples to illustrate systems for, and use of, thisapproach, including examples from Smalltalk andKEE®.

Almost everyone using a computer has received mes-sages from the operating system or other programstelling the user about actions to be taken or errorsfound. When a program is being written, the devel-oper must formulate the method by which the pro-gram will present such messages to a user. The paperby d'Arielli describes the use of a message manage-ment system in designing and implementing an ap-plication program for use on a personal computer.The system simply and effectivelymanages messagesfor the application. It reduces the coding work of thedeveloper while providing an improved method formessage handling within the program.

In this issue we also recognize the many refereeswhohelp us maintain the quality of the IBM SystemsJournal. They are drawn from academia, from thecomputer industry, and from within IBM. The list ofreferees for the last four years is included at the endof this issue. On behalf of the authors, readers, andeditors, we thank them for their conscientious efforts.

Gene F. HoffnagleEditor

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