"A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away.
Antoine de Saint-Exupery

Under Construction

Old is New Again

I have long been fascinated by old computers. The Digital Equipment Corporation PDP-8 is one of the most interesting. It embodies minimal. It was extremely small (physically and logically) and cheap. It was the first mass produced computer; over 300,000 were built. It was manufactured for over 20 years in over a half-dozen variations. The CPU went through several revisions during its life, from discrete transistors to single integrated circuit. And it introducted thousands of people to computers.

Over the years quite a few people have embarked on "reconstructions" of the PDP-8 in various forms. Now it's my turn. And I want to make it easy for others to build one, too. The goal is not a faithful reproduction of a full-blown PDP-8, but rather machine that looks like one and acts like one as much as possible while taking minimal space, time, and money.

The PDP-8 design is incredibly simple as processors go. Full design details and schematics are readily available on the web. Some people have faithfully reconstructed full-blown machines. Others have created simulators to run on your PC. Still others have re-created the machine in an FPGA. And some have found the (rare) single-chip PDP-8 CPU (Harris/Intersil 6100 and 6120) and built kits from those. A lot of people own PDP-8s, whether "real" or reconstructed. There are even some connected to the web that you can access from your browser.

The approach I am going to take is a bit different. I like the idea of using the single-chip CPU, but since they are rare and hard to find, another option was needed. So, I will make my own!