The PDP-11, the most influential minicomputer of all time @arstechnica
The Digital Equipment Corporation (DEC) PDP-11 is arguably the most influential minicomputer of all time – it helped popularize the interactive computing paradigm we take for granted today per a recent article in Ars Technica.
In today’s world of computing, in which every computer runs some variant of Windows, Mac, or Linux, it’s hard to distinguish between the CPUs underneath the operating system. But there was a time when differences in CPU architecture were a big deal. The PDP-11 helps explain why that was the case.
The PDP-11 was introduced in 1970, a time when most computing was done on expensive and large GE, CDC, and IBM mainframes that few people had access to. There were no laptops, desktops, or personal computers. Programming was done by only a few companies, mostly in assembly, COBOL, and FORTRAN. Input was done on punched cards, and programs ran in non-interactive batch runs.
Although the first PDP-11 was modest, it laid the groundwork for an invasion of minicomputers that would make a new generation of computers more readily available, essentially creating a revolution in computing. The PDP-11 helped birth the UNIX operating system and the C programming language. It would also greatly influence the next generation of computer architectures. During the 22-year lifespan of the PDP-11—a tenure unheard of by today’s standards—more than 600,000 PDP-11s were sold.
Early PDP-11 models were not overly impressive. The first PDP-11 11/20 cost $20,000, but it shipped with only about 4KB of RAM. But it also had an amazing orthogonal 16-bit architecture, eight registers, 65KB of address space, a 1.25 MHz cycle time, and a flexible UNIBUS hardware bus that would support future hardware peripherals.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.