1000BiT: Old computers manuals.
Altair Manuals: The following links are scans of original Altair, CP/M and other manuals in pdf format. Most manuals are searchable.
IBM 51xx PC Family Computers: This web site is intended to be a reference for computer-savvy people who are already familiar with the IBM 51xx PC family of vintage computers. This web site contains information that ranges from basic to very technical.
Manx: Manx is a catalog of manuals for old computers. Manx is an open source project hosted on CodePlex. This catalog mostly covers manufacturers of minicomputers and mainframes, or associated devices such as terminals and printers.
Microatena (ITA): Elenco libri e manuali
PDP-11.RU Mirrors Archive: A large archive of various mirror sites and consolidated information on retro computers.
replacementdocs: Have you ever rented a game that came with no instructions? Have you ever bought a used game and found out later that the package you received didn't come with an essential map or answers to copy protection questions required to play the game? Have you ever bought a re-released game and then realized that they only included an Installation Guide, no game instructions at all? Has your wife (or husband!) ever just thrown out all your game manuals because they thought “you didn't need them anymore”? If so, replacementdocs is here to help! We're here to provide you with those manuals for situations when you really should've had them to begin with.