Sunday, May 23, 2010

Friday Flashback: Screencast 90s style

While digitizing some old home movies from VHS-C magnetic tapes, I came across a 5 minute screencast that I created sometime in the mid 1990's. The term "screencast" dates from 2004. While I am certainly not the first person in the world to produce one, I did do it about 10 years before the name was coined. The program1 used to generate these images was written about 10 years earlier still.

Three segments, edited from the one recorded screencast, are presented here. The first one (57 seconds) describes a particular one dimensional cellular automaton, which generates a fractal pattern over time.

video

The next one (38 seconds) describes a different one dimensional cellular automaton, which demonstrates what is called a "glider". Over time a configuration of cells moves, in this case to the right. A mirror image of this configuration would move to the left.

video

The final segment (90 seconds) uses the same cellular automaton rules2 as the previous one, and shows what is called a "glider gun". As time progresses, this configuration of cells emits gliders regularly, first one moving to the right, then another moving to the left, and so on. In a wrap-around world, like the one I used in this Apple ][ program, the glider moving to the right soon meets up with the next one moving to the left and the two annihilate each other.

video

Creating a screencast with an Apple ][ was not difficult, and did not require any software, since this personal computer used an ordinary television set as its monitor. So it was a simple matter to take the output of the TV, using an RCA video cable, and connecting it to the video-in of a camcorder. The voice over was captured by the built-in microphone of the camcorder, as I operated the keyboard and watched the screen.
  1. I wrote the program myself, in 6502 machine language, in the mid 1980's. Unfortunately, this program no longer exists, being a victim of digital decay.
  2. The cellular automata rules come from a series of articles in Scientific American written by Stephen Wolfram. The subscription to Scientific American was initially a gift from a former professor (who was also influential in my decision to major in Computer Science), Dr. Alan C. Ashton.

Thursday, May 20, 2010

More on the bridge: less bridge

There is less and less left of the bridge (strictly speaking, a viaduct) that used to be part of North Temple, and part of my commute to work.

The section of bridge over 400 West is now completely removed.

The new viaduct will begin at 400 West and go up and over the railway tracks from there to 600 West.

Friday, May 14, 2010

Friday Flashback: Advanced Technology

Many years ago, in the early 1990's, I worked for WordPerfect Corporation in its Advanced Technology Group. One project with which I was heavily involved was using a PDA (Personal Digital Assistant) as a remote control for television.

I made a huge cardboard mock-up (about 3 feet by 18 inches and six inches thick) out of a cardboard box, with an image of the screen and controls pasted on the front. Also, we constructed a working prototype, using a PC connected to a universal remote control. The screen of the PC showed what would appear on the screen of the PDA, and the remote actually controlled a TV.

Now this has become reality! See this new app for the Apple iPad.

Other than the social networking feature (remember that our work was done before the Internet was widely known), we had foreseen all of the features shown in the video demo of this new app. Amazing what 20 years can do for technology maturation.

Thursday, May 13, 2010

Bridge out

I usually travel to work via North Temple, but the bridge over the railway tracks is being demolished!

Having to find alternate routes...