18 lines
		
	
	
		
			552 B
		
	
	
	
		
			Markdown
		
	
	
	
	
	
			
		
		
	
	
			18 lines
		
	
	
		
			552 B
		
	
	
	
		
			Markdown
		
	
	
	
	
	
# Sega Master System
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the predecessor to Genesis.
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surely had better graphics than NES, but its sound (fairly weak, 4ch PSG with A-3 is a lowest tone) is subject of several jokes.
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this console is powered by a derivative of the Texas Instruments SN76489.
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# effects
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- `20xy`: set noise mode.
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  - `x` controls whether to inherit frequency from hannel 3.
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    - 0: use one of 3 preset frequencies (C: A-2; C#: A-3; D: A-4).
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    - 1: use frequency of channel 3.
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  - `y` controls whether to select noise or thin pulse.
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    - 0: thin pulse.
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    - 1: noise.
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