After I implemented a memory mapped output, I was ready to make a sound card. The main concept behind the sound card was turning a piezo buzzer on an off very fast to make a tone. This tone would be a square wave, so it is a bit harsh on the ears (I plan to make it a sin wave in the future). The sound card uses a 1MHz clock, this is a signal that turns on and off 1 million times a second. Then my sound hard would use counters to control timing. finally the output to the piezo buzzer is connected to a sr latch. This latch is controlled based off the counters. The sound chip is able to play 256 tones in concept but the piezo buzzer's range causes issues for lower tones. Below is a video of my sound card playing the Blue Lobster jump scare meme sound.
Before I had the parts to make the sound chip, I made a prototype using the 3rd output as a sound output. I did this by having a variable stored in ram that would count up. When it reached a certain value it would flip the output and start counting again. This is the same concept as the sound card. The reason I made a sound card instead of just using the 6502 is that the sound card allows the 6502 to write one value then a tone is played. Without the sound card the 6502 has to spend all of its processing power on sound and it cant do anything else. Bellow you can see the 6502 method running through all of the frequencies.
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