I enjoy how everyone discovers this "feature." It really is a lot of fun to play with.
True story, back in the cave person days, when television only came over the air waves and if you wanted to "own" a computer you shelled out anywhere from $500 to $5000 for something with an 8 bit processor that ran between 1 and 4 MHz and had, usually, much less than 65,536 bytes of RAM, peripherals for these things were few and far between. A couple of serial ports and a couple of parallel ports was considered a "lot" of I/O. You might have stored your programs on an 8" or 5" floppy disk, but if it was before 1978 you most likely stored programs on cassette tape. Anyway ...
One of the things you could always count on was that these things radiated all sorts of spurious energy and being relatively low frequency beasts to begin with, finding a harmonic that you could pick up with an AM radio held "near" (where near could be 1' to 10' (.3 - 3m)) that interference and with the judicious use of delay loops cause that interference to modulate to "tones" and thus create recognizable "music."
As a kid in high school with just such a computer I can tell you that "playing music" (no matter how poorly) on a nearby AM radio was orders of magnitude more impressive than pointing out by the pattern of lit and unlit LEDs that your amazing machine had just calculated a logarithm. (even though the latter was significantly more difficult from a programming perspective!) Once I got a printer, being able to print out NSFW pictures was a neat trick but for crowd appeal and cheap accessories, music over an AM radio was still the top demo of the time :-)
It goes back even further than that. My father, at the time an operator on a Honeywell 6000, demonstrated a program (loaded from paper tape!) that played "Daisy" if you held a transistor radio next to the CPU. The choice of song was appropriate: 2001 A Space Odyssey had come out a few years earlier.
Fun fact: Radio Shack sold computer tape cassettes until the late 1980s for its TRS line. Incredible how they had decade old obsolete technology on the shelves.
That isn't unique to Radio Shack or the TRS line. Lots of systems (including Atari, Sinclair, Commodore) used cassettes well into the 80s, especially in Europe.
The last time I remember using a tape to save a program was in 1983. That's the year my dad bought the Peripheral Expansion System for our TI/99-4a, which came with a single-sided 5.25 inch floppy drive.
True story, back in the cave person days, when television only came over the air waves and if you wanted to "own" a computer you shelled out anywhere from $500 to $5000 for something with an 8 bit processor that ran between 1 and 4 MHz and had, usually, much less than 65,536 bytes of RAM, peripherals for these things were few and far between. A couple of serial ports and a couple of parallel ports was considered a "lot" of I/O. You might have stored your programs on an 8" or 5" floppy disk, but if it was before 1978 you most likely stored programs on cassette tape. Anyway ...
One of the things you could always count on was that these things radiated all sorts of spurious energy and being relatively low frequency beasts to begin with, finding a harmonic that you could pick up with an AM radio held "near" (where near could be 1' to 10' (.3 - 3m)) that interference and with the judicious use of delay loops cause that interference to modulate to "tones" and thus create recognizable "music."
As a kid in high school with just such a computer I can tell you that "playing music" (no matter how poorly) on a nearby AM radio was orders of magnitude more impressive than pointing out by the pattern of lit and unlit LEDs that your amazing machine had just calculated a logarithm. (even though the latter was significantly more difficult from a programming perspective!) Once I got a printer, being able to print out NSFW pictures was a neat trick but for crowd appeal and cheap accessories, music over an AM radio was still the top demo of the time :-)