Difference between revisions of "User:Tepples/Super NES vs. Genesis"

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(Audio: things Nikku4211 recommended that I point out)
(Audio: Nikku4211 on the SNESdev Discord listed a bunch of things that he considered conspicuous by their absence. Perhaps I left them out because I couldn't immediately find a way to make them flow in the narrative.)
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== Audio ==
 
== Audio ==
  
Super NES has a hardware sampler on a dedicated memory bus. This lets it mix up to eight sampled waves without a hiccup. Genesis audio, by contrast, is often scratchy as hell due to video DMA blocking the Z80, and mixing even two samples on the Z80 was seen as an accomplishment. One workaround is to use the FM voices wisely. Using the PSG for percussion or for an accompaniment line frees up FM channels. On the other hand, there's a lot more learning curve in creating patches for Yamaha OPN FM than for a sampler.
+
Super NES has a hardware sampler on a dedicated memory bus. This lets it mix up to eight sampled waves compressed with ADPCM-like Bit Rate Reduction without a hiccup. Genesis audio, by contrast, is often scratchy as hell due to video DMA blocking the Z80, and mixing even two uncompressed PCM samples on the Z80 was seen as an accomplishment. One workaround is to use the FM voices wisely. Using the PSG for percussion or for an accompaniment line frees up FM channels. On the other hand, there's a lot more learning curve in creating patches for Yamaha OPN FM than for a sampler.
  
 
To increase polyphony on OPN, use algorithm 4. All channels can play just-tuned dyads, much as a sampler can play chord samples. Channel 3 has a special mode to set the four independently to play two independent notes.
 
To increase polyphony on OPN, use algorithm 4. All channels can play just-tuned dyads, much as a sampler can play chord samples. Channel 3 has a special mode to set the four independently to play two independent notes.
  
OPN allows the modulator to decay over the course of each note, which produces a timbre that becomes gradually less bright. Approximating this on a sampler requires fairly large samples unless the driver sacrifices a voice to use the S-DSP's rarely used 2-operator FM mode.
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OPN and PSG produce overall brighter timbres than the S-DSP, which applies a Gaussian interpolation that tends to muffle high frequencies. OPN also allows the modulator to decay over the course of each note, which produces a timbre that becomes gradually less bright. Approximating this on a sampler requires fairly large samples unless the driver sacrifices a voice to use the S-DSP's rarely used 2-operator FM mode.
  
 
S-DSP lets the driver reserve a block of memory (usually on the order of 8 KiB) to capture the output and feed it back for echo. This can free up a voice or two compared to 2-channel echo techniques.
 
S-DSP lets the driver reserve a block of memory (usually on the order of 8 KiB) to capture the output and feed it back for echo. This can free up a voice or two compared to 2-channel echo techniques.
 +
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Both the PSG and the S-DSP have means to generate some form of white noise.
  
 
== Backward compatibility ==
 
== Backward compatibility ==

Revision as of 06:02, 31 January 2021

The WDC 65816 CPU in the Super NES is indeed slower than the Motorola 68000 CPU in the Sega Genesis (called Mega Drive outside North America) at some tasks. This doesn't mean the system as a whole is slower or otherwise inferior to the Genesis, though some advantages of the Super NES hardware aren't necessarily showstoppers either.

Color and resolution

The 5-bit-per-channel video DAC in the Super NES makes sky gradients less bandy than on Genesis. (Need counterpoint)

Super NES S-PPU has color math, which allows for mist or shadow with less hard edges than shadow/highlight mode of the Genesis. On the other hand, the Genesis's H40 mode makes pixels of striped or checkerboard layers small enough that the TV will blend them.

Some Super Famicom RPGs use its 512-pixel-wide hires mode for sharper text. This allows 21x14-pixel kanji glyphs (on a 24x16-pixel grid) in the space where a Mega Drive RPG in H40 mode would show 14x14 (on a 16x16-pixel grid). But given the typical capabilities of TVs of the time, 14x14 is already legible enough up to the composite video bandwidth limit.

Raster effects

Both the Super NES and the Genesis can horizontally scroll individual scanlines of a background plane for parallax. The Super NES uses a memory controller feature called horizontal blank direct memory access (HDMA) to poke the PPU in the background each scanline, whereas the Genesis uses a table of scroll positions in VRAM. The difference arises with any raster effect other than horizontal scrolling. Axelay stretches the background plane by an amount that increases down the screen for a "rolling log" effect. It does this by varying the scrolling Y coordinate with HDMA. The special stage in Sonic 3D Blast for Genesis shows the same effect, but the CPU has to stop and poke the vertical scroll between each scanline and the next.

Super NES has mode 7, a scanline rotozoomer that allows for behind-the-car racing games with a floor plane taking two-thirds of the screen. On the other hand, a 68K without the SVP can draw a height-mapped (or "voxel") landscape faster than a 65816 without the SA1 or GSU coprocessor.

Audio

Super NES has a hardware sampler on a dedicated memory bus. This lets it mix up to eight sampled waves compressed with ADPCM-like Bit Rate Reduction without a hiccup. Genesis audio, by contrast, is often scratchy as hell due to video DMA blocking the Z80, and mixing even two uncompressed PCM samples on the Z80 was seen as an accomplishment. One workaround is to use the FM voices wisely. Using the PSG for percussion or for an accompaniment line frees up FM channels. On the other hand, there's a lot more learning curve in creating patches for Yamaha OPN FM than for a sampler.

To increase polyphony on OPN, use algorithm 4. All channels can play just-tuned dyads, much as a sampler can play chord samples. Channel 3 has a special mode to set the four independently to play two independent notes.

OPN and PSG produce overall brighter timbres than the S-DSP, which applies a Gaussian interpolation that tends to muffle high frequencies. OPN also allows the modulator to decay over the course of each note, which produces a timbre that becomes gradually less bright. Approximating this on a sampler requires fairly large samples unless the driver sacrifices a voice to use the S-DSP's rarely used 2-operator FM mode.

S-DSP lets the driver reserve a block of memory (usually on the order of 8 KiB) to capture the output and feed it back for echo. This can free up a voice or two compared to 2-channel echo techniques.

Both the PSG and the S-DSP have means to generate some form of white noise.

Backward compatibility

Power Base Converter vs. Super Game Boy...

Input

Super NES comes with a controller with six action buttons: four face buttons and two shoulder buttons. Genesis eventually got a controller with six face buttons, but games have to be usable with the original 3-button controller, mapping the other three buttons' actions to (say) the sometimes awkward chord of Start+A, Start+B, and Start+C.