The PDP Planet site allows surfers to link via telnet into a working DECsystem-10 or an XKL Toad-1 (a DEC clone), and to create, upload or run programs.
The idea is to give today's computer users the experience of the early days of the computer industry.
"PDP Planet fulfils my dream to find a way to preserve the achievements of early computer engineers," said Allen.
"With running versions of these machines via the website, we now have a place that recognises the efforts of those creative engineers who made some of the early breakthroughs in interactive computing that changed the world."
PDP stands for Programmed Data Processor and DEC's first computer was the PDP-1 launched in 1960. It took up about 17 square feet of floor space, and its washing-machine-size disk drives each held a whopping 150MB of data.
The world's first computer game, Spacewar, was written on a PHP-1 in 1961 by Steve 'Slug' Russell, a member of MIT's Tech Model Railroad Club.
The first joysticks were invented by students to use on the game, which involved two spaceships trying to shoot each other while orbiting a star.
Allen and Gates started their computing careers on DEC machines. After using one via timeshare from their school mini-computer the pair arranged a deal with the University of Washington to allow them to use its DEC PDP-10 in return for debugging its software.
"My previous exposure to computer timesharing at Lakeside High School was my first foray into computing," explained Allen.
"Those experiences during my teen years began my interest in programming and technology, and changed my life."
Allen later used a self-designed emulator on DEC hardware to design a working BASIC operating system. Without this Microsoft would not have won some of its earliest contracts, according to his biography.
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