#pdp11

Mucho antes de que 𝐌𝐢𝐜𝐫𝐨𝐬𝐨𝐟𝐭 fuera sinónimo de Windows, también tuvo su propio UNIX: 𝗫𝗘𝗡𝗜𝗫.

Y uno de los capítulos menos recordados de esa historia pasa por el 𝙿𝙳𝙿-11 𝚍𝚎 𝙳𝚒𝚐𝚒𝚝𝚊𝚕 𝙴𝚚𝚞𝚒𝚙𝚖𝚎𝚗𝚝 𝙲𝚘𝚛𝚙𝚘𝚛𝚊𝚝𝚒𝚘𝚗, una de las minicomputadoras más influyentes de los años 70.

El 𝙿𝙳𝙿-11 fue una plataforma clave para laboratorios, universidades, telecomunicaciones, control industrial y para la expansión temprana de UNIX.

𝐌𝐢𝐜𝐫𝐨𝐬𝐨𝐟𝐭 licenció UNIX de AT&T a finales de los 70 y lo transformó en 𝗫𝗘𝗡𝗜𝗫, una versión comercial pensada para llevar el mundo UNIX a nuevas arquitecturas de 16 bits.

Aunque después se volvió más conocido en equipos 8086, 286, 386 y sistemas SCO, su raíz histórica está ligada a la cultura técnica del 𝙿𝙳𝙿-11 terminales, comandos, multiusuario, compiladores C y una forma de trabajar muy distinta a la PC doméstica.

𝗫𝗘𝗡𝗜𝗫 demuestra que la historia de 𝐌𝐢𝐜𝐫𝐨𝐬𝐨𝐟𝐭 no empezó solo con MS-DOS ni terminó en Windows. Hubo una etapa en la que la compañía apostó por UNIX como sistema serio para negocios, desarrollo y cómputo profesional.

🎄💾🗓️ Day 4: Retrocomputing Advent Calendar - The DEC PDP-11! 🎄💾🗓️

Released by Digital Equipment Corporation in 1970, the PDP-11 was a 16-bit minicomputer known for its orthogonal instruction set, allowing flexible and efficient programming. It introduced a Unibus architecture, which streamlined data communication and helped revolutionize computer design, making hardware design more modular and scalable. The PDP-11 was important in developing operating systems, including the early versions of UNIX. The PDP-11 was the hardware foundation for developing the C programming language and early UNIX systems. It supported multiple operating systems like RT-11, RSX-11, and UNIX, which directly shaped modern OS design principles. With over 600,000 units sold, the PDP-11 is celebrated as one of its era's most versatile and influential "minicomputers".

Check out the wikipedia page for some great history, photos (pictured here), and more -

And here's a story from Adafruit team member, Bill!

The DEC PDP-11 was the one of the first computers I ever programmed. That program was 'written' with a soldering iron.

I was an art student at the time, but spending most of my time in the engineering labs. There was a PDP-11-34 in the automation lab connected to an X-ray spectroscopy machine. Starting up the machine required toggling in a bootstrap loader via the front panel. This was a tedious process. So we ordered a diode-array boot ROM which had enough space to program 32 sixteen bit instructions.

Each instruction in the boot sequence needed to be broken down into binary (very straightforward with the PDP-11 instruction set). For each binary '1', a diode needed to be soldered into the array. The space was left empty for each '0'. 32 sixteen bit instructions was more than sufficient to load a secondary bootstrap from the floppy disk to launch the RT-11 operating system. So now it was possible to boot the system with just the push of a button.

I worked with a number DEC PDP-11/LSI-11 systems over the years. I still keep an LSI-11-23 system around for sentimental reasons.

RIP Gordon Bell, computer architect and vice president for Digital Equipment Corporation, responsible for the design of several computers in the PDP family as well as heading up the VAX system development group.

I couldn't blame you if you never heard of him, his contributions were mainly in the 1960s through 1980s. But trust me when I say, whatever device you are reading this on can trace its lineage back through some project he was involved with in one way or another.

When I worked for DEC, I used to love reading the internal DECNotes message board that had collected stories from Field Service about weird installations of our computers.

By far the best one concerned a PDP 11/73, like the one above, that was used to measure nuclear bomb yield. The story went that the system was in a shaft leading to the underground test chamber, and it took readings on the explosion in real time until it was vaporized.

I always hoped this was true but took it with a grain of salt - but this archive.org post about just such a setup at Los Alamos backs it up. The test method is quite ingenious too - the system uses time domain relfectometry (TDR) measurements to measure a length of cable between the bomb and the computer. As the bomb explodes, the blast eats away at the cable, and they can figure out yield and stuff based on how fast it happens.

The PDP 11 is indeed not spared in the process, it transmits its results to a distant receiver before being destroyed what can only be at most seconds later.