On a typewriter from around the time of the first Macs, the return key normally moves back to the beginning and moves down a line, so that's probably why they picked it. They also called the key "return" rather than "enter."
On a classic non-electric typewriter the carriage was returned by pushing a lever on the right side of the carriage. The lever could be pressed to the left relative to the carriage which would move the paper up. At the end of travel relative to the carriage if you kept pushing it would move the carriage back to the left. Hence CR and LF could be accomplished in one motion. If you wanted to advance the paper many lines, you'd push the lever multiple times - probably with the carriage all the way to the left the whole time.
On another note, I find it incredibly weird describing an "everyday" item like a typewriter because many people on HN may have never used one!
It's a simple mechanical artefact. Carriage return moves the paper carriage all the way to the right (returning it to its initial position), while line feed will advance the paper vertically (feeding a line through the carriage). With that in mind, line feed and carriage return on their own make about as little sense.
On later type writers both the line feed and carriage return were integrated into a single key or lever, which was just called carriage return or return. From this perspective, an encoding using a lone CR for newlines might make more sense than one using a lone LF. But neither combination really makes intuitive sense in buffered, electronic systems. It's just how it is.
Somehow the friends who told me how to use a PC always used "Return" instead of "Enter", but this was in Germany where we didn't have any text on this key, just a big arrow pointing down and left.
CR is a common line ending for RS-232 devices. I've got 3 or 4 in a cabinet for my current job which are "line-based" and which use CR as the line-ending. To issue a command to one of these devices, you terminate the command with CR and then the device processes it. These same devices will also send response data with CR line endings.
This is partly why stty and termios have options for CRLF translation on terminals. I'm sure there's some historical reason for that.
I thought it was to do with the fact that you might want to use them separately sometimes? For instance you might want to repeat a line without a newline for a "bold" effect, or with underscores for underlining.
It's no more odd than just 'LF'. At the end of the day, something has to represent 'end of line'. The outlier here is really MS DOS, wasting a perfectly good byte on pretend-lineprinter codes.
Ahh, you're correct. I wasn't sure if CRLF was actually codified in rfc158, I just did a search for "CRLF" on it, I didn't realise they were using the hex values of CR and LF (X'0D' X'0A').
The internet is now 8 or 9 million devices big, and CRLF is still the standard newline for internet protocols.
MS-DOS isn’t alone in that. https://en.wikipedia.org/wiki/Newline#Representations_in_dif... claims ”Atari TOS, Microsoft Windows, DOS (MS-DOS, PC DOS, etc.), DEC TOPS-10, RT-11, CP/M, MP/M, OS/2, Symbian OS, Palm OS, Amstrad CPC, and most other early non-Unix and non-IBM operating systems” used it.
The real surprise is the BBC Micro, which used LF+CR.
If I had to guess I'd say CP/M was developed for extra dumb teletypes that needed both to properly handle a newline. So many quirks in terminals date back to the days when everybody was just making it up as they went along. Legacy support is the root of most braindamage.
”The separation of newline into two functions concealed the fact that the print head could not return from the far right to the beginning of the next line in one-character time. That is why the sequence was always sent with the CR first. A character printed after a CR would often print as a smudge, on-the-fly in the middle of the page, while it was still moving the carriage back to the first position.”
There's an entry point in the BBC Micro's OS that's routine that prints a character, or LF+CR if the character is CR (13). This routine prints the CR second, so that when it was called with 13 originally it can fall through into the main, non-translating character print routine with 13 in the accumulator, and then return to the caller that way too. (These two routines promise to preserve the accumulator.) Saves a couple of bytes in the ROM.
(There's also an entry point partway through the wrapper that just prints a newline. DRY and all that.)
The code is not exactly this, but differs from it in no relevant way:
A lone CR is certainly more odd than a LF...LF is implicitly a new line. CR by definition is a return to the beginning of the line; literally NOT the end of the line!
Who would choose 'beginning of line' to mean 'end of line'?? Oh, Apple :)
There's nothing more 'implicitly new line' about either, in a text file. But if you're particularly set on hardware analogies - there's a 'return' key on keyboards and no 'line feed' one.
Umm, there absolutely is, unless you want to start using the backspace character instead of line feed or any other arbitrary swap, or maybe 'null', or 'delete'; Sure, 'null' should mean new line... 'Line Feed' by words, use and history, means new line....it feeds lines...i don't understand how you could make such an argument.
The fact that some keyboards say 'return' (but usually have a down-and-to-the-left graphic) is a separate issue, now that we are talking actual hardware; The lack of need for a specific CR, LF keys is obvious. Once again, of course today apple is using the odd choice of 'return', despite the rest of the industry. Many (most?) of 70s onward keyboards had an 'enter' key, no?
You're pulling things out of your ass. I'm interested in comments like yours. At some point between reading the previous comment and responding to it, you must have had some thought that goes, roughly, "Hey, I'm just going to make some shit up now and post it." Right? How else does it happen?
Apple's is not the only ecosystem that settled on carriage return. Who do you think was around for them to deliberately break compatibility with in 1977? Kildall?
Then the people who want to compile it rather than complain about it would have to go through an extra hoop to fix it again. They published it the right way.
That is an excellent point although I suspect your question is going to be answered in spades when people notice who the developer posting the code is.
Agreed, at least make sure it will still compile with line endings changed before submitting pull requests.
This builds with CodeWarrior 10 (from 1996) which is probably OK with non-Mac line endings, but there are other old Mac codebases on GitHub using older toolchains that require CR.
(i.e. Pararena 2: http://bslabs.net/2016/11/13/building-pararena/)
A PPC Mac running OS X 10.4 is basically the only way to work with both git and classic Mac dev environments, I'll be trying this out myself.
A year or two ago I built dropbear on Power MachTen, worked great and just needed a couple fixes to bring it back into compatibility with GCC 2.x.
Playing around with Professional MachTen (for 68k) is a real trip though. 4.3BSD, an even older GCC, and it implements virtual memory and protection by taking over the system memory manager. (You actually have to restart when quitting it)
It would be so cool to have something like MachTen on iOS, some people have tried but the restrictions on executable pages really restricts things.