Extremely brief history of PDP computers

# Extremely brief history of PDP computers Source: [https://entropicthoughts.com/history-of-pdp-computers](https://entropicthoughts.com/history-of-pdp-computers) I don’t know why I started to put this together\. These machines fascinate me, because so much of early computing/hacker type culture happened on them\. I started writing a table, but realised a timeline would be more intuitive\. In this graph, the price is for a minimal configuration and adjusted for inflation\. The time is the memory cycle time, a decent proxy for speed\.  Some notes: - Thepdp\-1 was created mostly as an experiment\. At the time, industrial control systems used either humans or complicated contraptions of logic boards to make decisions\. Some engineers atdecwanted to see if there was a customer base willing to use general\-purpose computers instead\.11But it wasn’t called a computer then, because the word “computer” back then meant big mainframe systems that ran batch calculations\. - Thepdp\-4 was a variant ofpdp\-1 that was a little slower and much cheaper\. It was not compatible with thepdp\-1\. Thepdp\-4 was upgraded with new chip technology and became thepdp\-7, which was then optimised further for cost and speed and became thepdp\-9\. - Thepdp\-5 was created when they realised thepdp\-1 andpdp\-4 machines were overkill for industrial control systems\. By being smaller, it could be much cheaper, at the cost of compatibility withpdp\-1 andpdp\-4\. It was still intended for roughly the same market\. The chip upgrade turned it into thepdp\-8\. - Thepdp\-6 was a completely different beast, aimed at a different market\. It supported having tonnes of directly\-addressable memory, as well as memory protection, so it could be used as a time\-sharing system\. The amount of memory made it run Lisp well\.22The smaller machines could also run Lisp, but not large Lisp programs\.With the chip upgrade, it became thepdp\-10\. - Thepdp\-11 was a new architecture again, intended to subsume all the previous models, to avoid running three incompatible lines in parallel\. There were many variants of thepdp\-11, with various performance characteristics and corresponding price points\. However, even its most powerful configuration wasn’t powerful enough to attract manypdp\-10 users\. - Thevaxcame much later, but it’s included in the table anyway because it is what eventually subsumed thepdp\-10\. Thevaxwas somewhat compatible with thepdp\-11, but they served different markets\. There is a noticeable split in the hacker culture between users of the smaller \(18 bit and less\) and larger \(32 bits and more\) computers, exemplified by the contrast between Unix and Emacs\. Unix was first created onpdp\-7, then ported topdp\-11, then distributed to otherpdp\-11 users\. The fact that it needed to run on these smaller machines, and still handle time sharing, shaped much of its implementation and interface\. The same thing is true of the C language and standard library\. Then we have something like Emacs, which was created on the massivepdp\-10, and gained popularity with otherpdp\-10 users\. It had plenty of hardware resources to use, and it did\. The same thing is true of many Lisp variants\. What decided whether you became a small\-computer hacker or large\-computer hacker was what your employer could afford\. Unix was created at Bell Labs, a private company that tried to do more with less\. Emacs, in contrast, was built atmit, which at the time was flush withdarpamoney\. This is why Richard Gabriel calls it[“mit/Stanford style” and “New Jersey approach”](https://www.dreamsongs.com/RiseOfWorseIsBetter.html)\. Some other examples of things that were developed on thepdp\-11 includes Usenet,`vi`,rsx\-11 \(another operating system whose lineage continues into Windowsnt\),`make`, the idea of a shell with composable commands, plus tiny programming languages like`awk`\. Things that were made with thepdp\-10 includes Scheme, TeX, Zork, email, and Microsoftbasic\. What do I want to say with this? I don’t know\.