I signed up for the 2009 RetroChallenge
Write a Y2K-compliant Biorhythm program on and for the original Apple II computer, using a vintage color TV.
Here is the Biorhythm video:
Apple II and Biorhythm Photographs
In order to run the program as intended, load Biorhythm on an Apple II 16K through a television by using one of the special RF signal generators made for the Apple II (Click for image). These hacks were sold by third-party companies such as the M & R Enterprises' Sup 'R' Mod. II because FCC regulations, I am told, disallowed the kit to be shipped with the original Apple II. The RF signal generator was connected to a video output circuit on the mother board.
Biorhythm makes use of the hi-res mode available to Apple II, especially the split screen capabilities. There was something special about the way Apple signals interacted with the old color TV sets to produce color and fine details. You can run Biorhythm albiet with a less-sharp picture by using the Apple's standard composite video (RCA jack), emulator or LCD.
The YouTube.com video shows the program in action, and you can see the forementioned distortions. Also, old TV sets return the scan lines when videoed and you'll see a little bit of that.
The biothythm program itself was written by me in Applesoft Basic for the 16K Apple II and it took about 30 hours to complete. This does not include finding suitable television.
Biorhythm autoloads with DOS 3.2 or 3.3. In theory any date from 0001 to 9999 will return the correct biorhythm, but remember that AD 1752 is when the leap year system was implemented. On-screen directions teach and guide a person through how to generate a biorhythm.
WHY DO THIS?
Apple, Atari, Tandy, nor Commodore seem to have offered a Y2K compliant biorhythm. I could be wrong. My version is an attempt to to make a Y2K compliant "classic". The old programs usually allowed dates from 1901 through 1999. Back then the extra two digits took up valuable memory and non-20th century dates were considered less important.
My version will calculate Captain Kirk's biorhythm and other future dates. Knock yourself out.
So why is the chick in the video reading the Byte Magazines?
There were no Apple brand video monitors until 1980. All of the old ads show people using television sets. Note in the video there is a poster-sized image of the original Apple II advertisement from Byte magazine.
I paired the Apple II with a 1969 Sony Trinitron. I imagine that most people would have used one of their older tv's for the "new" Apple II, not the main family set.
The end product
I have for all intents and purposes reproduced how an Apple II would have functioned, looked and been used - in 1978.
port the code to a disk image, post photographs of the RF signal generator, and motherboard.