PDP-1 was the first computer in DEC's PDP series and was first produced in 1960.
The PDP-1 is most famous for being the computer most important in the creation of hacker culture, at MIT, BBN and elsewhere. It was also the original hardware for playing the first computer game, Steve Russell's Spacewar.
It used punched paper tape as its primary storage medium. Unlike card decks, which could be sorted and re-ordered, punched paper tape was difficult to physically edit. This inspired the creation of text-editing programs such as Expensive Typewriter and TECO. Because it was equipped with online and offline printers that were based on IBM electric typewriters, it was capable of what, in eighties terminology, would be called "letter-quality printing" and therefore inspired TJ-2, arguably the first word processor.
MIT hackers also used it for playing music in four-part harmony, using some special hardware--four flip-flops directly controlled by the processor (filtered with simple RC filters). Music was prepared via Pete Samson's Harmony Compiler, a sophisticated text-based program with some features specifically oriented toward the efficient coding of baroque music. Several hours of music were prepared for it, including Bach fugues, all of Mozart's Eine Kleine Nachtmusik. Christmas carols, and numerous popular songs.
It had an 18 bit word and had 4K words as standard memory, upgradable to 64K words. The core cycle time was 200 nanoseconds (5MHz). Memory accesses took 5 microseconds; consequently most arithmetic instructions took 10 microseconds (100000 Operations per second) because they had two memory cycles: one for the instruction, one for the datum.