Speaking of SOUND... just for fun, I worked up the aforementioned "UFO Sound" in the foreground on a SN76477 that I had kicking around. It was a masterpiece until I screwed up the layout not realizing that this protoboard had a grid within, but it works now. I also have the schematic above (Space Invaders STEP sound) implemented in the background of the pic (the four buttons) and yes, Ben Eater's clock and 65C02 that you also see in this pic will drive this shortly.
Between the UFO and discreet transistor STEP sound circuit is the AMP circuit built up according to the 1980 Williams FirePower Pinball sound board.
A lot of the older arcade games used dedicated circuits to produce a particular sound effect. I think Donkey Kong used that kind of tech as well. Nice project there, man!
I also have the schematic above (Space Invaders STEP sound)
I'm a little lost - the schematic you posted was a bitmap with no SN76477 but your recent picture shows one in it. I've skimmed https://en.wikipedia.org/wiki/Texas_Instruments_SN76477 to get a better understanding of this circuit.
Any chance of posting a schematic of what you have built? Or is that mute because the chip is no longer being made as far as I can tell.
You can indeed buy SN76477, just don't buy them from China (as I did); the cockroach style are either fake or faulty; I blew about $60 on qty. 4 and they were all garbage. Instead, check synth-houses.
As for the schematic, I'll get you the one I used later tonight when I'm home but had this in my laptop; it's quite similar. I think this was from a cocktail schematic; the standup version depending on revision is slightly different. The line heading East from pins 12 & 13 is the audio output which is mixed with the other discrete circuits... the southbound line hits an inverter cell (on a 7404 between pins 1 & 2). This one uses 5V in to pin 15; some use the built in 9V input on ping 14 which outputs 5V on 14 (confusing, I know). I much rather send regulated +5V into pin 15 as they do here though I recall mine had/has a resistor in line. On this pic, lines 1, 19, and 22 are held 'high'. The inverted pin 9 is simply the 'start' / 'stop' sound which is autonomous and free running at a given frequency otherwise (built in low-free LFO drives the pitch). I can put up a 1 minute video of mine running if interesting to anybody.
I bought an SN76477 from Radio Shack in the 80s. I wasn't up to the challenge. But it was cool.
I've got a few of AY3-891xA chips in a very mixed collection of IC's from the 80s. Someday I'll get to them, but I like the 556/7411 circuit above as getting it going as it doesn't involve programming ? . The Vic 20 sound chip was understandable for a 80's teenager; audio programming on the X16 seems to be a much large area given the number of options it has. I'll be happy with whatever the x16 ships with, given my lack of musical talent. That would be my dream combination, since I really don't know any better.
My choice of combination would be a YM2151 with a YM3012 D/A converter, two SAA-1099's and a OKI MSM9810 which has twice the Channels than the OKI MSM6295 and it's cheaper.
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