Software Testing Topics

AS/400 Basics

What is AS/400 System?

AS/400 is midrange computer. It is designed and build as total system. This means that facilities such as a relational database and a networking capability are fully integrated into the operating system and the machine. The user communicates with all these functions through a single control language, or by using the system menus and prompts. AS/400 is designed as a general-purpose business computer.

AS/400 is designed and build as a total system. This means that facilities such as a relational database and a networking capability are fully integrated into the operating system and the machine. The user communicates with all these function through a single control language, or by using the system menus and prompts.

AS/400 is designed as a general-purpose business computer; it is optimized for that environment. Its design reflects the dominant requirements of the environment, which are:

  • Ease of use (from the operator’s, and end-user’s, point of view).
  • Ability to grow and improve the system without disruption.

Optimization for work in the commercial environment, which is Input/Output-intensive, rather than compute-intensive.


What are the basic system concepts for AS/400 systems?

  • Layered machine architecture

This insulates users from hardware characteristics. It enables them to move to new hardware technology at any time, without disrupting their application.

  • Object Orientation

Everything that can be stored or retrieved on the system is known as “object”. Objects exist to make user independent of the internal structure of the machine.

  • Single-level storage

Main storage and disk storage appears contiguous. An object is saved or restored on the system via a device-independent addressing mechanism. This means that extra main storage or disk storage can be added to the system and used without affecting the application program. A user or a programmer is not concerned as to where a program or file is; if they want to use it, they simply name it.

  • Hierarchy of microprocessors

AS/400 has a large number of microprocessors. Every input/output (I/O) device type on AS/400 has its own microprocessor. This means that requests for data to be read from I/O device can be delegated to the processor in change of that device. Meanwhile, the main System Processor executes another application.

  • Operating System

The software that controls the allocation and usage of hardware resources such as memory, central processing unit (CPU) time, disk space, and peripheral devices.

  • AS/400 Operating System

OS/400 is a single entity, fully integrating all the software components (relational database, communications and networking capabilities, etc.) needed for most commercials computing environments.

  • OS/400 Features

Online education
Multiple operating environments (S/36 & S/38)
Connectivity to Remote Devices, Systems and networks
Office Services
Powerful Data Recovery Options
Ease of use with Task oriented approach, Consistent format
and "Powerful and Flexible facility"


System Architecture - Comparison between Traditional System vs AS/400 system

Traditional system

  • Application program
  • Separate operating system components
    • base OS function
    • security product
    • communication product
    • database product
    • other OS product
  • Machine instruction

AS/400 system

  • Application programs
  • Single operating system
    • base OS function
    • Communication
    • database
    • security
  • LIC and hardware
    • Machine instruction , processor, memory etc.,