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Drew asks:

… what was the latest terminal produced which rang a physical bell rather than beeping through a speaker?

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2 Answers 2

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To my memory real bells were only a thing with TTYs. After all, ringing a bell is just another lever to be moved when a character comes along - the very same way as any other printable character.

I would not know of any Glass TTY that had a mechanical bell - after all, as soon as there's a TTL circuit to do the job, adding a flip flop and a resonator is already way less expensive than adding any bell mechanic.

This goes already with early printing terminals like the DECwriter series. Already the 1970 LA30 Decwriter (I) housed a rather bulky speaker unit as seen at the start of this video:

LA30 interior with speaker

That black bulky unit right in the middle produced what DEC calls a 'audible tone':

1.2.2 Bell Operation

Receipt of the Bell character causes an audible tone to be produced. A separate tone burst is produced from each of up to eight bell codes received in succession.

(From the LA36 Manual)

Each 'audible tone' is 106 ms of 2400 Hz. This is true for all DECwriters (LA30, LA36 and LA120).

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But there is a nice 'intermediate' step: Some early (high end) CRT terminals of the 1960s had circuitry that synthesized not just a beep but a more sophisticated bell like sound. For example die Siemens 8150 mainframe terminals and follow up series (8160 and early 9750).

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    Trying to revive long dormant brain cells, I can't remember if the DECwriter terminal I used in the mid 1970s had a physical bell or a speaker which produced and electronic sound when control-G was pressed. DECwriter terminals printed on folded paper, with sprocket holes along the sides, but had a dot matrix printing head.
    – Fred
    Dec 25, 2022 at 6:12
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    @Fred, You just fired one of mine (Brain cells, that is.) I am remembering the sound in the Carnegie-Mellon University computer center's public terminal room, circa 1980, whenever CMUC would crash. The front end would send the same message to thirty-ish terminals at the same time, "^G^G^G%% Decsystem 20 not running." I hear the electronic beeps of ten-ish LA36 DECWriters and twenty-ish assorted glass TTYs, A quiet zipzipzip sound as the DECWriters printed the message, a moment of absolute silence, and then thirty-ish voices all whispering in unison, "Oh Shit!" Dec 25, 2022 at 13:25
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    The Andromeda Strain would have turned out a lot differently with an LA-30!!!!!
    – RonJohn
    Dec 25, 2022 at 17:09
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    @scruss Please look here. I didn't change the core content at all. The edit only incorporated information about DECwriters. I first put them as answer to a comment by Fred, but realized that it might be good with the Answer as well. In fact, it even restricts the 'real bell' phase further by narrowing down to TTY only.
    – Raffzahn
    Dec 25, 2022 at 18:45
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    @Raffzahn: thank you again for being so informative, regarding the DECwriter.
    – Fred
    Dec 26, 2022 at 0:17
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I think the Teletype Model 43, ~ 1980, included a mechanical bell. It has been a while - I got rid of mine around 1986. The service manual references a "bell coil" and "bell plunger" in trouble-shooting for "Does bell ring under any conditions (CTRL G RH margin, etc)?", which implies that it is a mechanical bell of some sort rather than a purely electronic beep.

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  • When I last used a type 43 (1976), the bell rang at around column 72, telling you that you had 8 characters left before you reached the end of line. On a standard typewriter, this is normally set at 10 before end of line. Also, the programming languages at that thime (Algol 60, Fortran IV, Cobol) were restricted to 72 chars per line.
    – cup
    Dec 26, 2022 at 7:49
  • @cup The docs are pretty clear about the margin "bell". The only question is whether it was a true mechanical bell or not. Dec 26, 2022 at 15:40
  • Thank you for revive another of my brain cells. I remember using such terminals in the early to mid 1980s.
    – Fred
    Dec 27, 2022 at 7:06
  • @cup - the 'Algol 60' language had no such line-length limitation. Maybe your implementation did. I don't recall any such limit on the KDF9 Algol 60 compilers when presenting the program on paper tape, but it could have just been that I never bumped up against it.
    – dave
    Dec 29, 2022 at 10:13
  • It probably was the limitation on the ICL1900 implementation. I remember the first program I ever wrote didn't compile because the semicolon was in column 73. If I had submitted the program on the teletype, the bell would have told me but I submitted it on cards so there was no such warning.
    – cup
    Dec 29, 2022 at 18:53

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