A kick-ass mid-range computer invented by IBM. Long family tree going back to System/3 (and probably before). Updated through the years at hardware and software levels and today forms a very fine platform on which to build quality enterprise systems. Oh yeah, and don't forget RPG (Report Program Generator) one of the dogs of the programming language world that seems to follow AS/400 round.

IBM have now started calling them iSeries eServers or some old bollocks like that. Whatever. To droves of ageing programmers (who still think the RPG Debugging Template, flowchart stencils, Dire Straits, Jethro Tull, real ale, war gaming and cricket) are all 'cool', they represent a rock to cling to.
"I love AS/400's - they're the best goddam box to poke around in - even beats the milf's I pick up at bars after a long day spec'ing RPG programs." Hiram J. Corksacker III, Software Engineer, Portland, OR.
by Wizards Sleeve May 30, 2005
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When one goes hard on a fool, and shows they real and ain't a joke
"I down and went 400 on that nigga"
by YoungBloodPiru April 5, 2015
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is a blood gang in harford county that runs a quarter of Edgewood
damn 400 juss jumped another kid
by 21cabbage $$ January 7, 2018
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Gang number, referred to as the Four corner hustlers (400) "four" pronounced as foe.
Yeah we don't mess with them, they 400.
by $av March 16, 2014
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HTTP status code for 'bad request', usually due to an error in syntax.
He got a 400 error at that site, what could have caused it?
by madept April 2, 2004
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1) The 400th positive integer
2) Short for 400 metre dash
1) I counted to 400 today
2) I ran the 400 today
by thegreatwhitehype October 8, 2003
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She's been waiting..

She's been missing..
He can get enough of her.
She’s never been

So lonely like this...
Looking at the calendar 🗓️
And it 10/15
343 ..is real in an imagination world.
But 400 is reality.
by Renaissance® October 16, 2021
by JVeverMind April 19, 2023
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