Grant:
Like the idea of the Digital to Analog Converter. The main problems with the Kenbak is lack of input and output. The DAC going to a Volt-Freq. Converter would allow a pretty interesting project.
I'm glad you checked output light signals. I had figured they would not be a steady logic 0 or logic 1, but didn't know how significant the glitch would be. Your quantification of the glitch isn't bad. A low-pass filter (capacitor) would easilly smooth this, as I suspect notes would only change every 100 milliseconds or less.
The 555 timer idea is interesting. The history of the 555 timer is right here
http://semiconductormuseum.com/Trans...zind_Index.htm
The inventor says Signetics first produced them in 1972, so it's about the right vintage. Interesting, they say the 555 timer is the most produced IC of all times, an order of magnitude above the competition.
We could read from a table of notes and durations to play a song, but what fun is that? It would be cool if an algorithm could produce an interesting recurring sound? Has anyone ever seen a "music" algorithm that gives a fairly interesting complex "song-like" tune? Preferably without too many instructions? If you search for "music algorithms" on google, you get a ton of links. But something simple that can be machine coded into a handful of bytes? I don't know. I suspect we really need music algorithms from the 1970's, before hobbiests had good access to modern machines with unlimited memory and high level languages.
- Steven.