Emulate PSG in SN76489 mode for pre-SMS consoles - #150
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Internally it was trying to say SN76489AN = SMS/GG, SN79489 = SG/SC (Sound Type in drivers.h) so I felt I had to rename this. I also introduced a different enum for this in the PSG emulator. Overall I also want to throw away this PSG emulator because it's kind of inaccurate compared to modern ones. But that's for another time. |
maxim-zhao
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May 12, 2026
| #define NoiseWhiteFeedback_SMSGG 0x0009 // Bits 0 and 3 | ||
| #define NoiseWhiteFeedback_SGSC 0x0006 // Bits 1 and 2 | ||
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| #define NoiseWhiteFeedback NoiseWhiteFeedback_SMSGG |
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None of these were used
maxim-zhao
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May 12, 2026
| for (int i = 0; i < 4; i++) // FIXME: to be done in sound.c ? | ||
| PSG.Channels[i].Active = TRUE; | ||
| SN76489_Reset (Z80_DEFAULT_CPU_CLOCK, Sound.SampleRate); | ||
| SN76489_Reset (Z80_DEFAULT_CPU_CLOCK, Sound.SampleRate, NOISE_MODE_SEGA); |
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It gets reset later anyway so the noise mode doesn't matter
maxim-zhao
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May 12, 2026
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| #define TECHINFO_LINES (14) | ||
| #define TECHINFO_COLUMNS (90) | ||
| #define TECHINFO_COLUMNS (100) |
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Need more space...
maxim-zhao
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May 12, 2026
| // resume_fm(); | ||
| FM_Reset(); | ||
| SN76489_Reset (g_machine.TV->CPU_clock, Sound.SampleRate); | ||
| SN76489_Reset (g_machine.TV->CPU_clock, Sound.SampleRate, g_driver->snd == SND_SN76489 ? NOISE_MODE_SEGA : NOISE_MODE_SN76489); |
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Here's where we actually set the chip type into the PSG emulator
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Somehow Meka was always emulating in SMS mode. The difference is barely noticeable for white noise, but very noticeable for periodic - but then SG games hardly ever use that.