Making the SD card works the same way it did with AMH. Make sure it's a fresh format, FAT32, 32 kilobyte allocation size. This can be done with Windows or Mac.
Download the latest ZIP file, and extract the folders to your computer first, THEN copy them to the freshly formatted SD card and stick it in the machine. Hold the PROG button during startup, or use the menu to select Update on Next Boot. It takes about 3-4 minutes.
OK so WHY this specific update routine with the SD card?
Remember "Disk Defragmenter?" So what happens is, files aren't always contiguous on a disk especially if you overwrite or add files. One half of a file might be here, and the other half is somewhere else.
In a file allocation table, the "path" to complete a file is called a cluster chain. It points to the start of a file, how much of it is there, and at the end is a vector leading to the next cluster. You must "follow" this to get the entire file. Defragmenting reconnects file parts and makes them all contiguous. This is less of an issue with modern systems as you're not actually moving a read head across space to find the next part of a file.
Problem is, pinHeck doesn't use a "proper" file system and thus can't follow cluster chains. On boot, it scans the DMD and SFX folders, each of which contain up to 26 folders (A-Z) which contain around 50-60 files each. The directory sector for each folder is stored in RAM, so when a file is called, the system never has to "deep dive" through folders to find it. A "DAA.wav" file is stored in SFX/_D folder, so based off the first character, we know exactly where to start looking. We also never store more than 64 files in a folder, meaning the most files we ever have to search through looking for a match is 64 (and we only have to compare 2 characters as the first character is the folder pointer) Worst-case file seek time is 5ms which is 6 times faster than a single frame of video
The disadvantage is that we need a predictable "flat" file structure, which is why you must format an SD card before putting files on (but fast format is OK!) When you copy files to a blank card, everything is laid out nice and neat in contiguous order.
David and I discussed making a "pack" file - which would be a single file with out own directory structure inside (PC games do this) but that would be down the road.
It's also possible that we've optimized enough other stuff that we could "afford" to follow cluster chains again. But for now, this is still a massive improvement over how AMH was updated.