AS/400 Processor Specifications

By Michael Gunderson

IBM introduced their Application System/400 (AS/400) computer series in 1988. The AS/400 series was designed for small to mid-sized businesses. In 2000, the AS/400 family was succeeded by the IBM eServer iSeries. An AS/400 server can simultaneously host websites, facilitate e-business, mine databases, run applications such as enterprise Java and native Lotus Domino, process traditional applications like payroll and human resources and perform other tasks essential to day-to-day business operations.


The architecture of the IBM AS/400 processor has 12.7 mm CMOS ASIC chips utilizing 0.8 μm lithography and 0.5 μm channel lengths that provide outstanding silicon performance and allow the processor to meet density requirements. Five fundamental architecture principles define the IBM AS/400 architecture: technology independence, object-based design, hardware integration, software integration and single-level storage.

Input Output Interface

IBM AS/400 processors have high performance, ceramic, multi-chip modules and digital slope-controlled off-chip drivers that facilitate I/O (input/output) performance and resolve high simultaneous switch requirements. An I/O bus extender composed of serial fiber optic links addresses the larger processor to I/O device distance requirements.

Phase Clocks

An IBM AS/400 processor has four phase clocks that are designed to meet functional requirements. A distributed phase-lock loop and an automated procedure to balance clocks on the logic chips minimize system clock skews and ensure accuracy.


Logical partitioning (LPAR) technology and high availability clustering solutions developed by IBM can be found in their AS/400 series. LPAR enables one server to function like twelve separate servers. This offers an ideal solution for business computing operations, such as server consolidation, business unit consolidation, mixed production, test environment processing and integrated cluster management.


There are various models of IBM AS/400 processors with different disk capacities. Lower-capacity models have as low as 64 to 192 MB of memory, while higher-capacity models have as high as 1024 to 32768 MB of memory. The IBM AS/400 processor's 64-bit address space can address up to 18 quintillion bytes of data. The AS/400 processor architecture is designed to address up to 128-bit address space.

Direct Access Storage Disk

IBM AS/400 processors are designed for information intensive operations, which involve performing simple operations on a huge amount of data. Direct Access Storage Disks (DASD), which are attached directly to the server or computer, allow the AS/400 processors to manage anywhere from 4 GB to over 18,000 GB of data.

Expansion Support and Connectivity

As a server, an IBM AS/400 computer is capable of hosting workstations or other computers. The IBM AS/400 processor has twin axial and ASCII controllers to facilitate connections and communication between various devices and the server. Other expansion support and connectivity options include a fax IOP (input output processor), CD-ROM, optical libraries, communication lines, internal and external tape and LAN ports.