Talk:Errata: Difference between revisions
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It seems this should be easy to mitigate with HVBJOY/$4212. My question is whether reading $4212 flips off the vblank flag like NES $2002, or if instead the correct thing to do is keep reading it until the vblank flag reads clear? - [[User:Rainwarrior|Rainwarrior]] ([[User talk:Rainwarrior|talk]]) 05:24, 22 May 2022 (UTC) | It seems this should be easy to mitigate with HVBJOY/$4212. My question is whether reading $4212 flips off the vblank flag like NES $2002, or if instead the correct thing to do is keep reading it until the vblank flag reads clear? - [[User:Rainwarrior|Rainwarrior]] ([[User talk:Rainwarrior|talk]]) 05:24, 22 May 2022 (UTC) | ||
: Or does reading RDNMI/$4210 have the NES-like behaviour of clearing it? Can't quite tell from the description if that's only when NMI is already enabled. So... at least bit $4012 / bmi should be sufficient before enabling NMI, but possibly bit $4210 would do it in one instruction and skip the wait? - [[User:Rainwarrior|Rainwarrior]] ([[User talk:Rainwarrior|talk]]) | |||
: Yes, it has the same behavior as on the NES —[[User:Lidnariq|Lidnariq]] ([[User talk:Lidnariq|talk]]) 08:10, 25 May 2022 (UTC) | |||
== White noise generator == | |||
"The hardware noise unit uses the contents of an LFSR to generate a signed noise sample. Because the LFSR only shifts 1 bit per sample, the correlated lower bits end up producing a strong highpass filter effect on the noise.[8] Especially in the high and low ranges, this will differ from the more typical 1-bit LFSR noise sound seen in other sound chips." | |||
Despite being familiar with sound synthetis and electronics, this is not understandable to me. Is there a way to rephrase this to point out what is specific on the SPC700's white noise generator ? | |||
[[User:Bregalad|Bregalad]] ([[User talk:Bregalad|talk]]) 10:59, 28 November 2024 (UTC) | |||
Latest revision as of 10:59, 28 November 2024
The stuff on this page definitely needs to be double-checked, and ideally tested on a SNES where applicable. These issues don't seem to be documented very well online, and I've had to rely on forum posts and bits of documentation here and there about problems. - NovaSquirrel (talk) 05:54, 21 May 2022 (UTC)
NMI enable mid-vblank
"If NMI is enabled during vblank, NMI will trigger immediately."
It seems this should be easy to mitigate with HVBJOY/$4212. My question is whether reading $4212 flips off the vblank flag like NES $2002, or if instead the correct thing to do is keep reading it until the vblank flag reads clear? - Rainwarrior (talk) 05:24, 22 May 2022 (UTC)
- Or does reading RDNMI/$4210 have the NES-like behaviour of clearing it? Can't quite tell from the description if that's only when NMI is already enabled. So... at least bit $4012 / bmi should be sufficient before enabling NMI, but possibly bit $4210 would do it in one instruction and skip the wait? - Rainwarrior (talk)
White noise generator
"The hardware noise unit uses the contents of an LFSR to generate a signed noise sample. Because the LFSR only shifts 1 bit per sample, the correlated lower bits end up producing a strong highpass filter effect on the noise.[8] Especially in the high and low ranges, this will differ from the more typical 1-bit LFSR noise sound seen in other sound chips."
Despite being familiar with sound synthetis and electronics, this is not understandable to me. Is there a way to rephrase this to point out what is specific on the SPC700's white noise generator ? Bregalad (talk) 10:59, 28 November 2024 (UTC)
