brainwagon

I’ve been playing with a BASYS2 FPGA development kit from digilentinc.com, and pondering the world of digital system design. I chose the BASYS2 because of its low price ($70) and because it included a reasonable number of LEDs, switches, a VGA interface and a connector for a PS/2 keyboard. Still, I’ve been looking for other […]

I’m kind of on a retro computing kick for the last few weeks. I suppose it is mostly because I picked up an FPGA board to experiment with, and I have been reading old books on computer architectures, looking for old fun machines that were simple enough to implement in VHDL/Verilog. This brought me back […]

A couple of months ago, I did some simple simulations of light refracting through raindrops in a hope to understand the details of precisely how rainbows form. The graphs I produced were kind of boring, but they did illustrate a few interesting features of rainbows: namely, the double rainbow, and the formation of Alexander’s band, […]

As I have mentioned before, I sometimes find it convenient to write raw PostScript. I’ve used it to generate business cards, to make templates for laying out parts for radios and telescopees, and generating score cards and labels. Today, I had an idea for creating a large poster to hang in my office. It turns […]

A few years ago I spent a couple of hours tinkering with implementing Thad Walker’s scheme for printing computer generated holograms (see the link for the paper): Printing Holograms on a Laser Printer A recent comment has got me thinking that I should revisit the idea and the paper. For reasons which aren’t entirely clear […]

I needed a graphic of a flag that I could scale to whatever size I needed. About 10 minutes of Postscript hacking with the specifications in Wikipedia yielded the following results: Sadly, the syntax highlighter that I have here doesn’t know about PostScript, so I’ll just have to add it here. %!PS % % % […]

Tom and I have been discussing some early hacking efforts, probably spawned in part by my re-reading of Levy’s Hackers. A couple of days ago, this resulted in me pondering the mysteries of Minsky’s circle algorithm (still ongoing), but today it drove me to an early interesting sound algorithm documented in the legendary HAKMEM, ITEM […]

Tom and I took a quick break after work today to try lofting my Canon camera up in the air. We used the Picavet that Tom constructed, and ran a simple uBASIC script that just took a snapshot every five seconds. We shot a total of about 120 shots, about one fourth of which were […]

Another of my attempts to make pictures from volume data…

Well, i’ve had a couple of days to muck around with the ASUS WL-520G (hereafter revered to as “the ASUS” or “the router”) and OpenWRT. I have had a modicum of success, as well as a modicum of failure, so I thought I’d give an update. For my beacon transmitter, it is important that the […]

People who read this blog might have noticed that I have a love of devices that have firmware that can be subverted for other purposes. I have a Canon SD1100 that runs the CHDK firmware. I have a couple of Linksys WRT54G routers. I have an old NSLU2 that I haven’t goofed around with in […]

At the Maker Faire this weekend, I picked up a Waveshield kit for the Arduino. It’s a cute little board with an SD card interface, an I2C DAC, and a little op amp circuit to provide an audio interface. It took me about an hour and a half to solder together (I’m slow, but careful) […]

Okay, before I get too excited, I’ll disclose that Cake was set to a time limit of around 1 second, which limited it to just a few ply (maybe 9 typically) and I was letting MIlhouse think a little harder (still taking less than 10 seconds typically). Still, it’s good: it means that sparring matches […]

I finally got around to totally ripping out the old implementation of transposition tables, and installing a new one based upon hints I read about on various web pages, mostly originating with some of the ideas for cache management that Ken Thompson implemented for his chess program Belle. The idea is to implement two caches, […]

As some of you may have noticed, I occasionally like to write small programs to compute odd little mathematical curiousities. Something I hadn’t done in a long while was to use the Sieve of Eratosthenes to compute a bunch of prime numbers. I suspect that I wrote such a program very early in my exploration […]