geekabit

For my 22nd birthday Tom Blauwendraat (also known as 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 modern Linux as well. It is fun to see this old text adventure on my reasonably new system today.

Source code is available in the downloads directory.

If you'd like a visual tour of the same student house, here is one.

This adventure inspired a text adventure of their own at ACKspace.

The next gift is by Jeroen Domburg (also known as 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 ways that do not make any 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 V, just enough to power the thing. Some of the parts make an oscillator, connected to the blue 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.

A couple of years later Jeroen teamed up with Arjen Meek (also known as Ironhand) 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 exactly the unit is. Apparently it's a hardware Tetris-unit. They made a fully functional Tetris implementation on an 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 decoupling caps. For powering from the handshake lines there are a couple of diodes, two green leds used as zener diode and an electrolytic capacitor. 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 had 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.

This hardware tetris unit inspired the Serial ASCIImation project.

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.

Source is available in the downloads directory.

I have asked my friends and they were willing to release all material into the public domain, just like I do with my own projects.

All design files I have are included in the downloads directory of this article.