What is AS400 ?

Written by AS400i · 2 min read >

The AS400 (AS/400) is a popular family of mid-sized computer systems which can also be used as multi-user computer systems. By this, we mean that a single computer can interact with more than one user at a time. It was first introduced by IBM on June 21st, 1988. The ‘AS’ stands for “Application System”.

iSeries (AS400)
iSeries (AS400)

Use of AS400

The AS400 can be utilized for different business facets. Some models are designed as systems that provide resources to other computers, also known as a “server” in a network of computers, while others are set up for use with terminals or “display stations”.

Operating System

OS400 is the operating system for the AS/400. The AS/400 computers offer more compatibility across the product line than the earlier System/3X computers. Hence, the earlier IBM models of the System/36 and System/38 have since been replaced by the AS/400 systems.

Why AS400 is important

IBM has sold over 600,000 AS400’s and over 350,000 of them are still active. From distribution warehouses to hospital administrators, and even manufacturing companies, It is a strong component in aiding these companies’ daily business operations. The AS/400 utilizes a green screen interface, a built in database that resembles DB2, and a vast array of software to provide business solutions for today’s business needs.

Evolution of AS400

In October of 2000, IBM rebranded the AS400 and announced its name as the eServer iSeries. As part of IBM’s Systems branding initiative in 2006, it was again renamed to System i. The codename of the AS/400 project was “Silver Lake”, named for the lake in downtown Rochester, Minnesota, where the development of the system took place.

In April 2008, IBM announced its integration with the System p platform. The unified product line is called IBM Power Systems and features support for the IBM i (previously known as i5/OS or OS/400), AIX and GNU/Linux operating systems.



It includes an integrated DB2 database management system, a menu-driven interface, multi-user support, non-programmable terminals (IBM 5250) and printers, security, communications, client-server and web-based applications. Much of the software necessary to run the IBM System i is included and integrated into the base operating system.

The IBM System i also supports common client–server systems such as ODBC and JDBC for accessing its database from client software such as Java, Microsoft .NET languages and others.

AS400 Cloud

Large enterprises often run mission-critical workloads on AS400 applications that are older, difficult to maintain, and expensive to operate. Today, many enterprises want to migrate their workloads including their AS400 portfolios to the cloud in order to gain higher scalability, agility, and cost benefits.

At the moment this article written there are only few companies provide AS400 Cloud services and some of them are still in experimental level. Amazon infinite and Google AS400 host are few of them


Programming languages available for the AS400

IBM System i, supports plenty of languages you can not even learn nowadays. some of them you may never heard as a programming language even. List of supporting programming languages are mentioned below,

  • Assembly language
  • C
  • C++
  • Pascal
  • Java
  • EGL
  • Perl
  • Smalltalk
  • SQL
  • PHP
  • PL/I
  • Python
  • REXX

Several CASE tools are available

The ILE (Integrated Language Environment) programming environment allows programs from ILE compatible languages (C, C++, COBOL, RPG, Fortran, and CL), to be bound into the same executable and call procedures written in any of the other ILE languages.

The IBM System i fully supports the Java language, including a 32-bit Java Virtual Machine (JVM) and a 64-bit JVM.

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