AS/400

The original name for the ISeries still in use by many programmers and administrators. First sold in 1988, it was the direct successor to the System/38.

The original AS/400 hardware was based on a 48-bit proprietary CISC CPU, but was replaced with a 64-bit PowerPC RISC CPU. Even though the hardware platform changed, very few programs needed to be changed or even recompiled.

Silverlake was the codename for the AS/400 project before it was released. It was considered by many to be one of the worst-kept secrets.