38 lines
1.3 KiB
Markdown
38 lines
1.3 KiB
Markdown
# sound card with sn76489
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I accidentally stumbled across the sound chip sn76489. Since it can only be controlled via outputs, it is well suited for the extension-retro of lb3361.
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This is my attempt for a Gigatron sound card (Rev.3 still in work).
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Unfortunately, I haven't had any success so far in producing a reasonable sound on the board. Now I have finally discovered the cause of the problem.
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The SN76489 is available in two different pinouts. The difference is mirrored data pins.
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| SN76489 Pin | Pinout 1 | Pinout 2 |
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|:-------:|:--------:|:--------:|
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| 3 | D0 | D7 |
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| 2 | D1 | D6 |
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| 1 | D2 | D5 |
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| 15 | D3 | D4 |
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| 13 | D4 | D3 |
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| 12 | D5 | D2 |
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| 11 | D6 | D1 |
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| 10 | D7 | D0 |
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Pinout 1:
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https://map.grauw.nl/resources/sound/texas_instruments_sn76489an.pdf
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Pinout 2:
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https://en.m.wikipedia.org/wiki/Texas_Instruments_SN76489
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I solved the problem on the breadboard for now.
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I'm still testing a small adapter board. When she leaves I will post it here.
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I will also rework the PCB itself.
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First tests (fast cell phone video):
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https://www.youtube.com/watch?v=wv5x-WD0vzI
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