By connecting a small amplifier and speaker to the 1802's Q output line, users of ELF computers could produce sound simply by toggling Q at a desired frequency. TinyELF simulates this by monitoring the frequency of Q and sending the output to your computer's speakers. If you're simulating more than one ELF simultaneously, only the currently selected one sends its output to the speaker.
TinyELF simulates an ELF computer running at 1.789773 MHz. This peculiar frequency came about because these machines often used an inexpensive "colorburst" crystal used in color televisions, dividing the crystal frequency by two to drive the computer. Each machine cycle of the 1802 requires 8 clock cycles, and 1802 instructions take either 2 or 3 machine cycles (consult Appendix A of A Short Course In Programming). Generating the right frequency on the Q line, then, is a matter of doing a little math, then writing a program that carefully counts machine cycles and toggles Q with the SEQ and REQ instructions.
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To generate sound with TinyELF, run a program that toggles the 1802's Q output at the desired frequency (see the sample programs). The volume of TinyELF's sound relative to other applications may be changed in the Preferences panel. |