SPC memory allocation

[tomaitheous]

PCE, GBA: 16 background palettes and 16 sprite palettes
SNES: 8 background palettes and 8 sprite palettes
MD: 4 background palettes, and sprites share the background palettes

I think you missed the sarcasm in my post

In digital signal processing, "nearest neighbor" refers to the kind of resampling that one gets from a sample and hold circuit. Linear interpolation fits a linear curve across each sample period; Gaussian and cubic interpolation fit a smoother curve. The smoother curves are worse for representing square waves but better for representing sinusoids and other band-limited signals.

I know what nearest neighbor is; I'm asking what it has to do with PCE sawtooth and NES triangle? PCE is 5bit waveforms. In 32steps, all 32 amplitude values can be used. NES triangle peaks at 16 steps, then climbs down. How is that the same?

Anything above 7khz (per sample, not per 32 step cycle) on the PCE ramps towards the next sample (not the same as return to zero or decay to centerline). Something like a sawtooth climb has a nice smooth line (no stepping like you would think from 5bit PCM). Maybe because each channel has its own DAC, rather than digitally mixed and output on a single DAC.

[tepples]

In digital signal processing, "nearest neighbor" refers to the kind of resampling that one gets from a sample and hold circuit. Linear interpolation fits a linear curve across each sample period

I know what nearest neighbor is; I'm asking what it has to do with PCE sawtooth and NES triangle? PCE is 5bit waveforms. In 32steps, all 32 amplitude values can be used. NES triangle peaks at 16 steps, then climbs down. How is that the same?

PCE triangle would have steps 0, 2, 4, 6, 8, 10, ..., 28, 30, 30, 28, ... 6, 4, 2, correct?

Anything above 7khz (per sample, not per 32 step cycle) on the PCE ramps towards the next sample (not the same as return to zero or decay to centerline). Something like a sawtooth climb has a nice smooth line (no stepping like you would think from 5bit PCM).

From your description, that sounds like either a low-pass filter or linear interpolation. I'm curious as to how sound actually works on PCE. Is there a recording of a sawtooth period sweep, including parts below and above 7 kHz sample rate, that I could examine in an audio editor?

[tomaitheous]

From your description, that sounds like either a low-pass filter or linear interpolation. I'm curious as to how sound actually works on PCE. Is there a recording of a sawtooth period sweep, including parts below and above 7 kHz sample rate, that I could examine in an audio editor?

Not linear interpolation, 'cause I can tap the lines directly from the chip before the AMP circuitry and they look pure digital (although extremely high temporal res - on the scope). And the low frequency settings give the usual return to zero artifacts (causes a slight metallic sound to notes in octave range 1 - especially noticeable for sinewave sample). Given that, I guess it has nothing to do each channel having a separate DAC (although there are still artifacts from changing the volume for each channel - a spike that causes a DC offset to that channel, the decays back to the normal centerline).

I can do a recording sometime this week.

PCE triangle would have steps 0, 2, 4, 6, 8, 10, ..., 28, 30, 30, 28, ... 6, 4, 2, correct?

Correct.