Here is a template. If you follow this template for your binary file format's magic number, you will be doing it better than a depressingly large number of senior software engineers.
First eight bytes of the file:
0xDC 0xDF X X x x (0x01 0x00 | 0x00 0x01)
0xDC 0xDF are bytes with the high bit set. Together with the next two bytes, they form a four-byte sequence that cannot appear in any valid ASCII, UTF-8, Corrected UTF-8, or UTF-16 (regardless of endianness) text document. This is not a perfectly bulletproof declaration that the file does not contain text, but it should be strong enough except maybe for formats like PDF that can't decide if they're structured text or binary.
X X x x: Four ASCII alphanumeric characters naming your file format. Make them clearly related to your recommended file name extension. I'm giving you four characters because we're running out of three-letter acronyms. If you don't need four characters, pad at the end with 0x1A (aka ^Z).
The first two of these (the uppercase Xes) must not have their high bits set, lest the "this is not text" declaration be weakened. For the other two (lowercase xes), use of ASCII alphanumerics is just a strong recommendation.
0x01 0x00 or 0x00 0x01: This is to be understood as a 16-bit unsigned integer in your choice of little- or big-endian order. It serves three functions. In descending order of importance:
It includes a zero byte, reinforcing the declaration that this is not a text file.
It demonstrates which byte ordering will be used throughout the file. It does not matter which order you choose, but you need to consciously choose either big- or little-endian and then use that byte order consistently throughout the file. Yes, I have seen cases where people didn't do that.
It's an escape hatch. If one day you discover that you need to alter the structure of the rest of the file in a totally incompatible way, and yet it is still meaningfully the same format, so you don't want to change the name characters, you can change the
0x01to0x02. We both hope that day will never come, but we both know it might.
The PineNote is here! I'm planning on making a hands on video to share my experience. Let me know if you have any questions you want me to try and answer. I don't plan to do technical tests but open to collaborating on it.
First impression, feels like a quality and sturdy device. Feels good in the hand, the texture is a kinda soft grippy plastic. Pen felt good, the writing friction seems ok, I don't want to make any software qualifications until I update the device but still happy with the out-of-box experience. The wake from sleep time is essentially instant.
@PINE64 great work on the PineNote, I'm very impressed with the hardware!
Edit 2: there's renewed interest in this post, feel free to check out the first impressions video (~6 mins, which has a good bit of usage footage), in case that post isn't visible to you.
Edit: Link to blog post with thoughts after day one. Since I'm on a single user instance most people may not see the thread with info that hasn't been boosted, the post has all of it.
