Why do older files tend to have file extensions in all caps?

Back in the days of DOS/MS-DOS, all filenames were in uppercase and restricted to 8 letter filename and 3 letter extension.

Because Windows was always just built on top of DOS and the FAT filesystem, until NT/Win2000, the actual file naming convention renamed the same.

Windows just held extra metadata to pretend it could have longer filenames.

Others have correctly explained that this is because filenames (on DOS) used to have only uppercase letters.

Interestingly, it's not completely outdated. Many standalone digital cameras, even ones produced in the 2010s or 2020s, still produce filenames like IMG_1234.JPG or DSC00011.ARW or similar.

::: spoiler it was the style at the time

but actually (as the other comment says) uppercase file extensions were a holdover from when the entire filename could only be uppercase :::

It's because eyeglasses hadn't been invented yet, so we needed to make file names bigger.

Well sonny, it's because back then, media files would eat your entire drive in a hurry, so they had to be shouted out as a warning.

Back in the day when affordable homes were very much bigger compared to now. You could splurge a little on hard drives that could store big size letters. Now that affordable homes (tiny condos) are a teeny tiny bit smaller, it makes sense to shrink the size of the letters so that they fit in a smaller space.

Adding to the replies, uppercase letters have lower hexadecimal values than lowercase in the ASCII table. For example, 0x4C is uppercase L, while 0x6C is lowercase L.

Mathematically, uppercase + 0x20 = lowercase.

Alphabetically, 41 to 4f = A to O, then 50 to 5a = P to Z; 61 to 6f = a to o, then 70 to 7a = p to z. (Believe it or not, I'm typing this from meat memory, as I kind of managed to memorize it and I can even 74 79 70 65 20 6c 69 6b 65 20 74 68 69 73 as if it were a second language; it's thanks to mnemonic shortcuts such as alpha and Omega A to O, "PTZ" p to z, among other crazy pattern matching my ND brain often does).

Back in the DOS/MS-DOS times, RAM and (floppy) disk were very small (a floppy disk had <2MB, and I'm talking about the "modern" floppy disks from the 2000s), so there was this thing called "code golfing" in which programmers used to do some arcane math-magick to conjure as many bytes as possible from inside a single byte. Things like "packed" game sprite channels, side channel data (wonder how compression algorithms got created?), etc. They wouldn't and often couldn't "throw more hardware at the problem" like we're used to nowadays. Sparing the 3rd most significant bit (01x1 1010, Z if x = 0, z if x = 1) would allow for side-channel data such as visual formatting (e.g. whether the character is selected in a terminal emulator).

This all likely played a role when they got chosen as the default interval for alphabet letters back then. Also, decimal numbers, 0x30 to 0x39 (resp. 0 to 9) are closer to the uppercase letters than to the lowercase letters, and so are most of the punctuation (which I didn't get to memorize yet, but I remember they're scattered across 0x21 to 0x2f then 0x3a to 0x3f then 0x5b to 0x5f).

This legacy kind of still lingers nowadays, for example, in PC keyboards whose key codes for alphabet letters (afaik) map to the 0x41 to 0x5a range when it gets to the HID driver. Then there are also devices in which program logic is burned into IC chip, such as "old" digital cameras and camcorders, so they ended "frozen" in a time where the file extension was conventionally uppercase.

(And, no, I'm not a millennial, although I'm almost one, sitting at the very cusp between them and Zs, two generations who saw the transition from analog to digital tech during our childhoods/teens).

!nostupidquestions@lemmy.world

Because DOS/early Windows had a filesystem that had very limited filenames. You had eight characters for the actual filename and three for the file extension. They were stored and displayed in all caps, but matching was always case insensitive.

That explains both the upper case and the three character extension limit.

Worth mentioning that this wasn't a problem on other systems. Unix had long, case-sensitive names before DOS existed.

It can easily be answered by a simple google search.