AS400
Also known as: AS/400, Application System/400
The slashless form of IBM's original AS/400 brand name. Not the original official styling, but now the dominant search, typing, and colloquial shorthand for IBM i and IBM Power Systems.
AS400 is the slashless form of IBM's original AS/400 brand name. IBM launched the platform in 1988 as the Application System/400, written officially as AS/400. Over time, users dropped the slash in typing, job titles, URLs, file names, documentation shortcuts, and search queries, making AS400 the dominant colloquial and SEO form. On this site, AS400 is used intentionally because it more closely reflects how many searchers type and say the platform name today, even though AS/400 is the original IBM brand-correct form.