This is a loose collection describing my hobby projects in electronics over the past few years. I started with electronics a long time ago at a time when the technology was not as widespread as it is today. Transistors were very expensive and using 74xx as a hobbyist was the bleeding edge. Later I irregularly got back to this hobby but only since 2010 I was seriously resuming the hobby again. A few years later I focused on PDP‐11 related projects which will be the most important topic of this web page.

I’m a big fan of PDP‐11 and for a long time I have always wished that I could own one and be able to run RSX‐11M on it, which was the operating system that I was using at my first job.

At some stage I owned a PRO‐380 and even some parts of a small Plessey Peripherals system.

The PRO‐380 is gone as it someday no longer worked and I did not have the time, documents and means to repair it, so I dumped it, but only after I desoldered the DCJ11. Later this DCJ11 would turn into the reason I started with my PDP‐11/Hack project.

The Plessey Peripherals system was missing all of its peripherals and my know‐how about PDP‐11 hardware at that time was not sufficient to turn it into a real system. At the beginning I used to play with the Plessey system a little bit, using a PC power supply and some toggle switches to simulate the power-up sequence and I got to the point of at least having an ODT prompt and I could deposit and examine data to the memory but that was pretty much it.

For almost two decades these items were kept in a cardboard box and I almost forgot about them.

In 2014 I started to look seriously into the DCJ11 and step by step I built my first PDP‐11 around the CPU. Later I started to re‐animate the Plessey system and even built some custom Q-Bus cards for this system.

Today – thanks to the Internet – it is far easier to find the required information and get help from people with the same interests. Thanks to this, I was able to finish my PDP‐11/Hack project and bring the Plessey Peripherals System to life again.

On the home page you will find direct links to the PDP‐11 projects. Note that hobby projects are never finished and from time to time there are updates even to existing projects or boards I have been building and using. So the content may change randomly.

More.. brings you to my other electronics projects where I mostly just document some findings or present other work from my hobby. Many of these projects are one-shot work that I just wanted to share or document for myself.