A NES ROM that shows inputs with extremely high precision, targeted towards high level competitors in NES Tetris. Created using the wonderful NESFab programming language.
Using the MMC3's scanline counter, this ROM polls the controller 16 times each frame, for a resulting poll rate of around 16*60.0988Hz=961.5808Hz, which rivals the 1000Hz rate you might get from a USB adapter.
To download the ROM, simply head over to the release page and download the most recent version of roll.nes. A discussion of how to use the ROM can be found in the next section.
rollTool aims to work on a large variety of platforms. However, due to the precise nature of this project, perfect functionality across the board is difficult to coordinate. For example, basically all NES emulators used for actually playing games only poll the OS layer once per frame, so the tool will not work the way it should on any computer1.
Instead, the recommended way to use rollTool is with a console+cartridge setup. But even this is not clear-cut, as many alternatives exist for both the console and the cartridge. This can present problems of its own; for example, some clone consoles may not handle illegal instructions correctly, which older versions of NESFab made heavy use of.
Since I personally only have regular access to a retroUSB AVS, that's the only platform I can guarantee perfect functionality for. When releasing new versions, I will attempt to contact people with various common setups for additional testing, and this will be reflected in the release notes. The same goes for cartridges; I only have an Everdrive N8, but will attempt to test releases using the Kryzsiocart, as well as on other flash carts that I can contact.
If you aren't able to get rollTool working with your unique setup, check the comments of this issue, which tracks a working list of such problems.
This ROM is built with a development build of NESFab 1.4 (specifically commit 52e0a4), which is included in this repository as a submodule. Use git clone --recurse-submodules https://github.com/fractal161/rollTool to install everything with one command. To build the compiler, cd into the nesfab/ directory and run make release. Passing ISA=legal makes the compiler only output legal 6502 instructions, which is useful for compatibility with more clones. If you have already installed NESFab elsewhere and wish to use that, you'll need to configure the Makefile to point to your copy of the nesfab executable and configure roll.cfg to point to the necessary library files. However, this is discouraged, as different versions of the compiler tend to introduce subtle issues (e.g. small amounts of jittering) since some of the logic is sensitive to timing info.
In addition, you'll need some version of python, along with opencv2 if you wish to build chr/hz.png yourself (though this isn't necessary since the file is already provided.)
From there, run make in the root directory and you're done!
Footnotes
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The information will still be correct, but with a greatly reduced level of accuracy. ↩