SNES PPU Warmup Period?
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- gravelstudios
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SNES PPU Warmup Period?
Does the SNES have a PPU warmup period like the NES, or is it ready to go as soon as the console is powered up?
- NovaSquirrel
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Re: SNES PPU Warmup Period?
You can write to SNES PPU registers immediately after powering on the console. I think the only hardware you actually have to wait for is the APU.
Re: SNES PPU Warmup Period?
Yeah no warm-up needed, but initializing all the PPU and CPU registers (and clearing RAM, VRAM, CGRAM and OAM) takes some time as there are a lot of registers to write to (the official docs has a list of values to write to each register).
I guess the wait for the APU is waiting for the APU's IPL ROM to respond to your request which is what you do every time you upload code or data to it, so it's not only a warm-up time but part of the communication.
I guess the wait for the APU is waiting for the APU's IPL ROM to respond to your request which is what you do every time you upload code or data to it, so it's not only a warm-up time but part of the communication.
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Re: SNES PPU Warmup Period?
The reset signal goes from the CIC to PPU2 and from there to the rest of the system, so the PPUs are probably the first components ready for operation.
Then the 5A22 may or may not perform some initialization before starting up its 65c816 core; we won't know without some oscilloscope measurements and/or interpreting die scans.
And lastly, the CPU performs its own RESET interrupt sequence before the programmer's code is executed.
Then the 5A22 may or may not perform some initialization before starting up its 65c816 core; we won't know without some oscilloscope measurements and/or interpreting die scans.
And lastly, the CPU performs its own RESET interrupt sequence before the programmer's code is executed.
My current setup:
Super Famicom ("2/1/3" SNS-CPU-GPM-02) → SCART → OSSC → StarTech USB3HDCAP → AmaRecTV 3.10
Super Famicom ("2/1/3" SNS-CPU-GPM-02) → SCART → OSSC → StarTech USB3HDCAP → AmaRecTV 3.10
Re: SNES PPU Warmup Period?
Pretty certain there's no external bus activity from the 5A22 separate from the 65816 after reset - it would have shown up on some of poot36's logic analyzer traces.
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Re: SNES PPU Warmup Period?
Wait, the NES PPU had a warm up period?
Re: SNES PPU Warmup Period?
See the second bullet point here.
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Re: SNES PPU Warmup Period?
I meant internal initialization. We could in theory compare address/data bus recordings between a regular 65c816 and the 5A22 to see if the latter takes more time.
My current setup:
Super Famicom ("2/1/3" SNS-CPU-GPM-02) → SCART → OSSC → StarTech USB3HDCAP → AmaRecTV 3.10
Super Famicom ("2/1/3" SNS-CPU-GPM-02) → SCART → OSSC → StarTech USB3HDCAP → AmaRecTV 3.10