App Development

What is AS400?

What is AS400?

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The Good Old Days (For Some)

Back in the 70s and 80s, IBM was king in the computer world. Large enterprises automatically contacted IBM when they were looking for new computer systems.

Until SAP came along, some of the largest ERP (Enterprise Resource Planning) systems ran on IBM hardware; products such as MAAPICS, JD Edwards, JBA and Movex were amongst the most popular.

These applications were developed for use on IBM mid-range servers using the RPG structured programming language. The IBM mid-range developed from the System/3 back in 1969 and the first of these ERP systems started to appear on the System/34 which was introduced in 1977.  ERP systems provided medium to large size companies with a tightly integrated solution covering accounting, payroll, inventory, job costing, etc. instead of having to operate individual, disconnected systems.

In 1978 the System/38 was introduced and it was a major leap forward in terms of computing power and numbers of users. It had its own integrated relational database and integrated microcode.

The System/38 evolved into the AS400 in 1988 and 1000’s of applications have been developed for the AS400 in areas such as banking, insurance, manufacturing and retail.

Since then the AS400 has had several name changes such as iSeries, System i; its current incarnation is the IBM i. The “i” stands for integration.

Although considered old technology by many, the AS400 has kept pace with modern technology and now runs on PowerPC-based CPUs (Central Processing Unit). The use of power chips in the AS400 provides the ability to run two different operating systems on the same machine in different logical partitions

An-early-AS400-smaller-235x300.jpg An early AS400
  • The OS400 operating system is used for business applications and
  • The AIX(Unix) operating system for scientific applications.

FOLDOC Editor Denis Howe explains why the system is still used by many corporates:

“The machine survives because its API layer allows the operating system and application programs to take advantage of advances in hardware without recompilation and which means that a complete system that costs $9000 runs the exact same operating system and software as a $2 million system.”

Source: The Free On-line Dictionary of Computing,

Businesses run on their Computer Systems

Thousands of business applications have been developed for the IBM mid-range and still form the backbone of many computer systems in the aforementioned industries banking, insurance, manufacturing and retail. These applications have developed and matured over a period of 25 years and have business functionality that most of the modern Windows based applications can only dream about as a future development.

It is because of this richness in functionality many of these systems are still in use today running on the latest generation of the IBM i. It is also well-known for being robust and reliable.

IBM celebrated IBM i’s 25th anniversary earlier in 2013 and reflected upon AS400’ early days in this video:


Moving to a new platform can be a very extended and expensive process and at the end of this process the new system may not have the functionality of the old system. This is what we often hear from big corporate organisations.

Nevertheless, modernising has been at the agenda of many corporate businesses. We will address the topic how to modernise legacy systems in another blog post. 

If you're looking to move off as 400 and on to new technologies contact Lateral today!

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