How a bullet turns into a beep

re: How a bullet turns into a beep

cocobello — Thu, 04 Jan 2007 18:34:45 GMT

Ctrl+G=BEL

re: How a bullet turns into a beep

kiwiblue — Thu, 04 Jan 2007 18:40:54 GMT

Can't reproduce on XPSP2. I'm copying it into CMD.EXE console window, and echo actually copies the bullet character.

re: How a bullet turns into a beep

Rick C — Thu, 04 Jan 2007 18:58:25 GMT

On the other hand, if I try, also on XPSP2, it copies the bullet *and* beeps.

re: How a bullet turns into a beep

kiwiblue — Thu, 04 Jan 2007 19:03:08 GMT

Just tried "echo Ctrl+G", and it beeps nicely, so the internal speaker is OK.

re: How a bullet turns into a beep

Johannes Rössel — Thu, 04 Jan 2007 19:07:18 GMT

Whether this issue is reproducable depends on the settings for the command line window. Since I set my default cmd to Lucida Console some time ago it can actually display Unicode characters directly on the console. If, however, the window is set to use a raster font it only has the OEM codepage and will convert the bullet character into BEL which, on echo, will beep.

re: How a bullet turns into a beep

Nish — Thu, 04 Jan 2007 19:30:29 GMT

>> Type echo ^A where you actually type Ctrl+A where I wrote ^A. The result: A smiling face, ☺ U+263A.) <<

Raymond,

Isn't that behavior due to the fact that ASCII 1 is ☺ ?

re: How a bullet turns into a beep

jim — Thu, 04 Jan 2007 19:51:48 GMT

Interesting. A little experiment with a command prompt (XPSP2 again) reveals the following behaviour:

Most control characters display as ^char and echo as glyphs. ^C aborts. ^G "echos" as a beep only. ^H and ^I are interpreted by the line editor as backspace and tab, respectively. ^J seems to be ignored completely. ^K and ^L echo as glyphs only amongst other input; on their own they just give the "ECHO is on." message. ^M is interpreted as ENTER. ^S suppresses the next character. ^Z is the end-of-input character; anything after it on a line appears in the line editor but is not echoed.

Bored? Moi?

re: How a bullet turns into a beep

Carlos — Thu, 04 Jan 2007 20:02:50 GMT

jim missed out ^@, which seems to act as an end-of-input-on-the-current-line character, then prompts for more input on the next line. e.g.:

C:\>echo hello^@world

More? dolly

hellodolly

re: How a bullet turns into a beep

andy — Thu, 04 Jan 2007 20:06:44 GMT

jim's comment about ^Z reminded me of the article "Using the echo command to remember what you were doing." (http://blogs.msdn.com/oldnewthing/archive/2004/04/29/123012.aspx).

Instead of pressing the "home"-button and then typing "echo " you can just press the "home"-button and type ^Z (i.e. press CTRL+Z) and get the same effect. 4 keys less to type :)

re: How a bullet turns into a beep

Mike Dimmick — Thu, 04 Jan 2007 20:07:06 GMT

Nish: ASCII 1 is not ☺, it is Start Of Heading (SOH). It may be ☺ in IBM codepage 437, but that's a different thing entirely. Whether the 'C0 Controls' displayed as those symbols or performed their control function depended on which API you were using to display text. If you use the raw 'display a character' BIOS API or write directly into the display buffer, you get the display character; if you use the 'display a string' API the character is interpreted.

I wrote a library to help port from Symbol Series 3000 (DOS-based with an extended largely-IBM-compatible BIOS) to Windows CE. My implementation of the 'display a string' API currently doesn't emulate a teletype, so character code 7 produces a bullet rather than a beep. The C0 controls weren't actually used much in Series 3000 programs so we tend to fix the program rather than add teletype support to the library.

re: How a bullet turns into a beep

Nick Fitzsimons — Thu, 04 Jan 2007 20:38:50 GMT

Mike Dimmick beat me to explaining ☺, but to Carlos: CTRL-@ is equal to character code 0 (zero), which is ASCII NUL. The use of zero in C as a string terminator might have something to do with the behaviour you're seeing... or it might not :-)

If you look at an ASCII table, you can see that @ is character 64, and the action of the CTRL key is (nominally) to reset the sixth bit, so that CTRL-@ -> 0 == NUL, CTRL-A -> 1 == SOH, CTRL-G -> 7 == BEL and so forth:

http://www.asciitable.com/

re: How a bullet turns into a beep

Ben Cooke — Thu, 04 Jan 2007 21:05:17 GMT

Somehow I had completely forgotten that there were glyphs in those control characters in the olden days. You had me scratching my head for a few minutes thinking "why would a BEL be a bullet?!".

I'm sure lots of people of a suitable age remember making silly little demos/games involving those smiley face characters, the card symbols and the musical note. Those arrow characters were quite useful for scroll bars, too. I guess it would have been a waste not to use those characters for glyphs too, since those <32 values could be written to video memory just fine.

re: How a bullet turns into a beep

SM — Thu, 04 Jan 2007 22:16:58 GMT

(jim) >>"^J seems to be ignored completely ...^M is interpreted as ENTER."

That is interesting. The ^J should be a Linefeed, and ^M should be a Carriage Return. Of course, with windows files, a line ending is noted with the CR LF combination. I guess the enter key in cmd.exe only sends a CR?

re: How a bullet turns into a beep

Nick — Fri, 05 Jan 2007 00:41:01 GMT

So 'echo ^D' prints a diamond. D for diamond, it all makes sense now!

Regarding andy's comment, if I want to save what I've typed at a prompt, I usually don't press HOME at all. What I do (that works with Bash and CMD) is just press CTRL-C. This cancels and gives me a new prompt, but leaves whatever I had on the previous line intact. Very handy.

[But it doesn't go into the command history, which is might inconvenient. -Raymond]

re: How a bullet turns into a beep

Nick — Fri, 05 Jan 2007 03:29:07 GMT

[But it doesn't go into the command history, which is might inconvenient. -Raymond]

Ah, true enough. I didn't think about that.

An alternative that does require use of HOME is to type a colon at the start of the line. It gets treated the same as a REM and does stay in the command history.

re: How a bullet turns into a beep

Norman Diamond — Fri, 05 Jan 2007 07:32:57 GMT

> GetStockFont(OEM_FIXED_FONT)

I think you need to go into Control Panel and set your system's default language for non-Unicode programs. In fact even if your program IS Unicode I think you have to do that setting. I should read and experiment to see if AppLocale will take care of it. Anyway just getting the default code page changed doesn't get the default font changed.

> Type echo ^A where you actually type Ctrl+A

> where I wrote ^A. The result:

The result is a quotation mark. I think in a command prompt window the command "mode con cp select=" some number will adjust the font together with the code page.

[Sigh. "On a Windows XP machine in the default configuration for a US-English system." I assume people are smart enough to figure that out. Are you nitpicking or were you genuinely confused? I can never tell with you. -Raymond]

re: How a bullet turns into a beep

svark — Fri, 05 Jan 2007 08:57:20 GMT

>>Can't reproduce on XPSP2. I'm copying it into >>CMD.EXE console window, and echo actually >>copies the bullet character.

In the command window properties if the Font is chosen as Lucida it would print a bullet, otherwise if raster fonts is chosen it would sound a bell as Raymond noted.

re: How a bullet turns into a beep

kiwiblue — Fri, 05 Jan 2007 16:58:49 GMT

>> Can't reproduce on XPSP2. I'm copying

>> it into CMD.EXE console window, and

>> echo actually copies the bullet character.

> In the command window properties if the

> Font is chosen as Lucida it would print a

> bullet, otherwise if raster fonts is

> chosen it would sound a bell as Raymond

> noted.

As pointed by Johannes Rössel in 5th reply.

Beeps from bullets

Buck Hodges — Sun, 07 Jan 2007 01:05:41 GMT

Way back near the beginning of development of TFS version control, which was called Hatteras back then,

re: How a bullet turns into a beep

Igor — Mon, 08 Jan 2007 02:25:14 GMT

Happy New Year to Raymond. Perhaps associating bullet to beep is intentional ;)