Some gifts for me

published: by Maarten Tromp.

Here are some of the amazing gifts my friends have made me over the years.

Zork-inspired text adventure

project date: , project by Tom Blauwendraat, article by Maarten Tromp

For my 22nd birthday Tom Blauwendraat (aka antiflu) made me a text adventure. It is inspired by Zork, which I was playing at the time, and takes place in my own student home. It starts out in my room, where I am at my computer, and works its way down the house (literally).

At the time the code ran under DOS. With a little tweaking the code compiled just fine under Linux as well. It is fun to see this old text adventure on my reasonably modern system today.

Source code is available in the downloads directory.

Heap of electronic parts

project date: , project by Jeroen Domburg, article by Maarten Tromp

The next gift is by Jeroen Domburg (aka Sprite_tm). He has made me a puzzle; what does it do? It looks like a heap of old electronic parts soldered together, on the back of four eproms. Everything seems to be connected at random, leaving many pins not connected at all and others connected in a way that does not make sense. There's no power source but there are leds. There is even an electret microphone in the heap. Jeroen told me it really does something.

Once you put the heap in direct sunlight, things start to happen. It starts to tick, buzz and squeal, depending on the amount of light. Jeroen had noticed that eproms sort of work like tiny solar panels. The eproms on the bottom are not just for decoration, they are the power source. Combined they output about 0.7 Volt, just enough to power the thing. Some of the parts make an oscillator, connected to the piezo speaker in the middle. The other parts serve as decoration.

Even after all those years, the unit is still whistling away in the sun.

Hardware Tetris unit

project date: , project by Jeroen Domburg and Arjen Meek, article by Maarten Tromp

A couple of years later, for my 24th birthday, Jeroen teamed up with Arjen Meek and made me a black box. Connect it to a serial port and start a terminal emulator to find out what it does. Once you do this, and figure out the correct serial port settings in the process, you are greeted with a banner explaining what exatly the unit is. Apparently it's a hardware Tetris-unit. They made a fully functional Tetris implementation on the avr, outputting ASCII-art graphics over the serial port. The unit even drew its power from the serial port. It was just like a USB-stick, before we had USB-sticks.

Within minutes we took the unit apart, just to see what's inside. You can see the avr with crystal and caps. For powering from the handshake lines there are a couple of diodes, two green leds used as zener diode an a cap. Last there are some transistors for RS232 level shifting. Everything is built very compact and just fits into a DB9-to-RJ45 converter.

When I wanted to try the stick again, 14 years later, I found my computer no longer has a serial port. However with a USB-to-serial converter it worked just fine. The unit seems to have survived sitting on the bottom of my parts bin for over a decade.

Source code and schematic are available in the downloads directory.

Demo board

project date: , project by Jeroen Domburg and Tom Blauwendraat, article by Maarten Tromp

For my 27th birthday Jeroen brought me a board he had made for an Elektor magazine article. It is a home-etched board with a LPC2103F ARM7 microcontroller, Nokia colour display and electret microphone. The Elektor article was about an audio spectrum analyser, but this board does a bit more.

Together with Tom he has written numerous extra demos. There are a rotozoom featuring a birthday cake, text scrollers, a plasma and some spectrum analyser visualizations. They even continued to work on it while on the train on their way to my birthday party, to the surprise of the other people on the train.