Archive for category: Computer Science

Russ Cox muses about Fields and Reed-Solomon codes

April 10, 2012 | Computer Science, Math | By: Mark VandeWettering

I’ve been pretty interested in codes of all sort, both the cryptographic codes and the codes that are used to provide error detection and correction. While I’ve played around quite a bit with convolutional codes, I haven’t really every bothered to develop more than a cursory understanding of the Reed-Solomon error correcting codes which have […]

A Tale of Two Gadgets: the TonidoPlug 2 and a Bus Pirate…

March 30, 2012 | Hardware, Microcontrollers, My Projects | By: Mark VandeWettering

A few days ago, I mentioned that one of my servers had died. I spent some time thinking about how I would replace it. I like having a 24/7 hooked up to the Internet to serve as a file drop and a place where I can use SSH to connect to other devices on my […]

The Little Engine that Could…

March 23, 2012 | Hardware | By: Mark VandeWettering

In my home office, I have a machine called “fishtank”. I realized that I first bought it back in 2002, and since then it has been running various flavors of FreeBSD (probably beginning around 4.6 or so, currently running 7.2). At various times I’ve added or upgraded disk drives to it. While a power failure […]

Arduino Basic

December 23, 2011 | Arduino, Computer Science, Programming Languages | By: Mark VandeWettering

Edsger Dijkstra, Dutch computer scientist and winner of the 1972 Turing Award wrote: It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration. While I have respect for his great contributions to the field, in my […]

Microcontroller cheat sheet

December 13, 2011 | Arduino, electronics, Hardware, Microcontrollers | By: Mark VandeWettering

I needed to know the pinouts for various AVR chips and the 6 pin ICSP cable they used. I found this cool little one page sheet that had that, and more. Saved for future reference: Microcontroller cheat sheet.

More Wisdom on LEDs…

December 7, 2011 | Computer Graphics, electronics | By: Mark VandeWettering

More important help for the budding young electronics designer: Little known fact: If you wire up an LED backwards, it actually works as a dark-emitting diode. 12/7/2011 3:38 pm via webReplyRetweetFavorite @EMSL Evil Mad Scientist Note: this also works in computer graphics quite well. Just specify a negative intensity for the light value.

Making some wallpaper with the sum of cosines…

November 2, 2011 | Computer Graphics | By: Mark VandeWettering

I was inspired by some Haskell code written by keegan, so I had to write a version of it in C. I didn’t do any animation, but I did have a lot of fun playing around with the parameters. For instance, check out the code, and how changing the value of N from 5, 7, […]

Can we go beyond WSPR? An idea for beacon operations on amateur radio.

September 13, 2011 | Amateur Radio, Cryptography | By: Mark VandeWettering

I was interested in WSPR and visual MEPT oeprations for quite some time. I operated both a beacon and a QRSS aggregator on 30m for a while, but I grew a bit tired of it, and it’s been silent for a year or so. But I haven’t stopped thinking about them. In fact, I’ve had […]

Sprites mods – CP/M on an AVR

September 5, 2011 | electronics, Hacking, Hardware | By: Mark VandeWettering

I’ve always been fascinated by emulation and virtual machines, as well as retro-computing: resurrecting the old machines of my past. I never owned an old CP/M machine, but there are still some neat projects where people construct there own, and simulators like SIMH and YAZE-AG are good software simulators. But what I always wondered was […]

Donald Michie, Alan Turing, Martin Gardner, and Tic Tac Toe

August 28, 2011 | Computer Science, Cryptography, Games and Diversions | By: Mark VandeWettering

As anyone who reads my blog with any regularity will tell you, I like to read and learn new things. The problem with being self taught and also easily distracted means that you often learn a great deal, but don’t always perceive the connections and scope of what you are learning. I found another example […]

Return Infinity – BareMetal OS

May 28, 2011 | Computer Science, Operating Systems | By: Mark VandeWettering

At various times, I’ve been interested in writing operating systems. I haven’t done much thinking about this recently, but it is a topic of interest. I hadn’t seen this project before: a small 64 bit kernel written in assembly. I have no idea whether it’s interesting, but I thought I’d bookmark it for future investigation. […]

My trip down memory lane leads me back to TOPS-10 and the PDP-10

May 17, 2011 | Computer Science | By: Mark VandeWettering

I’m going to be nostalgic for a few moments. If you are too young to have any sense of nostalgia, skip ahead to the bold text below. You were warned! A few days ago, I mentioned that I was having a bit of flashback, thinking of my first experience with time sharing computers back in […]

Magnetic core memory reborn… on an Arduino????

May 11, 2011 | Computer Science, electronics, Hacking, Hardware | By: Mark VandeWettering

I may have mentioned before, I’m kind of old. One measure of how old I am is the fact that I’ve actually programmed machines that used core memory. Real core memory. Little ferrite donuts on arrays of wires. Some time ago, I remember running across this awesome blog post from “Wayne’s Tinkering Page” which showed […]

Word squares…

May 4, 2011 | Computer Science, My Projects, Puzzles | By: Mark VandeWettering

I like to read the Programming Praxis website. Every post challenges you to write some simple programs to boost your skill, akin to finger exercises for a musical instrument. Today’s challenge was an interesting which intrigued Charles Babbage: creating word squares. I spent about 10 minutes writing one in Python that worked rather well: here […]

A small standalone homebrew computer: FIGnition by Libby8dev

May 1, 2011 | electronics, Hardware | By: Mark VandeWettering

I’m old. I learned to program as a teenager in the 1980s. Back then, we learned to program on small microcomputers. These machines weren’t very powerful, but they had a neat feature: they were self-hosted. In recent years, a large variety of small microcontrollers have become popular. Many of these have capabilities far in excess […]