@b0rk @ben Yes, it gets quite "hairy" with "cooked...

Yes, it gets quite "hairy" with "cooked mode" and such.

The interface to ASCII terminals is based on teletypes, where the "Enter" key is "Carriage Return" (^M = 13). On output, to "go to the start of the next line," you need to send "Carriage Return" (^M) and "Line Feed" (^J).

And that's how "new lines" are stored in Windows (from MS-DOS, from CP/M), because CP/M was kind of crude and "dumb."

Unix files use '^J' for "new line." So it has to translate ("cooked mode") on I/O.

Like 8 July at 19:53 | Wall-to-wall | Open on mastodon.social

5 comments

Ben Cox

@JeffGrigg @b0rk Yeah it's actually a pretty good way to get a good range of characters and consistency on input from a limited device like a tty or an early terminal.

What I had forgotten about (until someone, maybe @cks ? reminded me) is that the driver does similar transformations on output as well.

8 July at 19:58 | Open on pgh.social

Mark Eichin

@JeffGrigg
Tiny historical detail (which may be both obvious and not very relevant, I'll admit) missing here: the names are what those codes *do*, ie. Return the Carriage (or print head in fancy devices) to the first column, Feed the platen by one Line, etc. (Form Feed ^L ejecting a whole page kind of mutated to "clear"...)
@b0rk @ben

9 July at 1:26 | Open on mastodon.mit.edu

DHeadshot's Alt

@JeffGrigg
The ASCII standard specifies CRLF as a line ending: this is the rare occasion when Microsoft are following an (albeit outdated) standard when Unix-like systems aren't!
@b0rk @ben

9 July at 23:04 | Open on topspicy.social

Jeff Grigg

@ddlyh @b0rk @ben

Mainframes traditionally use fixed-width record sizes to represent "lines." (Or "cards" if you really think their way.)

Unix, C, C++ '\n'. (And '^D', not stored in the file, for end of file.)

CP/M, MS-DOS, Windows: '\r\n', the physical representation for most "terminals." (And '^Z', in the file, for "end of text in this file." With "junk" to fill the rest of the fixed-size block.)

Original Apple Mac: '\r' (or so I've read)

PICK OS: hex 'FE' character for line separator

10 July at 0:17 | Open on mastodon.social

Jeff Grigg

@ddlyh @b0rk @ben

The "logical" representation, stored in memory or disk, does not have to correspond exactly to the "physical" representation sent to the terminal/printer.

But in CP/M's case, it does simplify things: No translation; just dump text file contents to the console stream, "raw." The implementation of the "TYPE" command is "stream bytes until you hit '^Z' or end of file, and stop."

10 July at 0:20 | Open on mastodon.social