Reverse emulating the NES to give it SUPER POWERS!

Note that some of these features require special hardware support in the cartridge. The NES cartridge connector exposes CPU and PPU (picture processing unit) pins, and the simplest games ("NROM") connect ROM chips directly to them. More advanced designs add an additional memory management controller (commonly called a "mapper"): [link] The animated backgrounds are accomplished by the mapper bank switching the character (tile) memory. The parallax scrolling is accomplished by the mapper counting scanlines and generating an interrupt when the correct scanline is reached, so the CPU can change the PPU scroll registers mid-frame with the correct timing. Later mappers like the the MMC5 could precisely time mid-frame bank changes to support more than 256 tiles on screen at once, and to support 8x8 attribute blocks instead of 16x16. The ultimate mapper feeds arbitrary data to the PPU to simulate having a bitmapped display with 8x1 attribute blocks (the PPU only reads attribute memory once every 8 pixels, so that's a hard limit). Tom Murphy implemented this with a Raspberry Pi (which isn't ideally suited to the task, so there are timing imperfections causing graphical glitches, but theoretically it could be done without them): [this video]

When seeing Prettier as a software tool, to consider Prettier more “foundational” than (e.g.) TypeScript or V8 does seem like an inversion of hierarchy [1] – but viewed as history, as a practice, Prettier’s accomplishment of making automatic code formatting (à la `go fmt` or Python `black`) widespread in JavaScript, the lingua franca of programming, is foundational. All that time spent staring at code that could have been more readable, or writing style guides and reformatting code, is now spent doing what we were trying to do in the first place. And now, speeding up the time we wait to apply formatting or check it in CI by rewriting it in Rust™ gives us a bit more of that time back. :) [1]: [this video]

That you can plug legacy x86 extension hardware into the board, and have it find a bug-for-bug-compatible x86 system to talk to on the other end. A major use-case being embedded systems — e.g. industrial control systems. These systems use a combination of 1. custom hardware — usually in the form of peripheral cards — built to speak old legacy x86-only bus protocols like ISA; and 2. old custom software, designed to run on an x86 CPU (usually in DOS), and to speak directly to that hardware over that bus. You can't just find some USB adapter for the old hardware's bus, because the software won't take it. And you can't just replace the old software, because the new software (whether a newer version of the old software, or software from another vendor) won't control the old card; and the card speaks an even lower -level (probably analogue!) protocol specific to the industrial system. Often, on these old systems, the custom peripheral card is still working due to it being solid-state (and thank god for that; the card's vendor is probably long-gone!) but the old x86 box the card lived in for the last 40 years is dying of various old-computer maladies — or just can't be made to fit into a new form-factor forced by a newer generation of the industrial system being controlled. In such a case, you ideally want to find a new embedded host system, made of new parts that will last you the next 40 years, but which can nevertheless still talk in very specific, custom, low-level ways to your