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Where have you actually come across a 555 timer in the wild?

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fcb:
I once found one buried in the carpet. It left 8 little holes in my foot.

ErikTheNorwegian:
A wild 555 cought by the cat, right before it was to eascape out the window... and into the wild!


amyk:

--- Quote from: T3sl4co1l on April 01, 2014, 10:37:03 pm ---
--- Quote from: magetoo on April 01, 2014, 10:02:11 pm ---Historic note: In the original PC, the timer chip had three separate timers - it generated a periodic interrupt at 18.2 Hz for DOS, drove the speaker with another timer, and also did a third thing I can't remember.

--- End quote ---

Third is actually the first (timer 0): interrupt for the DMA controller to perform another DRAM refresh.  Every couple of microseconds I think.

The 18.2Hz is used by the clock (at least when DOS is handling it, I think?).  You can hijack the interrupt and use the count for something else (say, an in-game timer to trigger another frame of activity), but don't be surprised if your system time is running slow afterwards. ;D

This, by the way, is precisely why, if a motherboard had a 555, it's not used to generate PC tones: the timer has a pin toggle mode which does it directly.  Give or take a driver for the PC speaker (2" 8 ohm in the old fashioned models, usually some piss tiny piezo these days).

All this stuff was integrated first into a SuperIO chip (along with all the other system functions, and serial and parallel), then into the South Bridge when that become a thing.  If your motherboard has a BIOS, it has all of this stuff in it somewhere; UEFI models may not, I don't know.

Tim

--- End quote ---
If you saw a 555 on a mobo, chances are that it's some other 8-pin IC with that marking code and not the timer. Ever since the first PC, its main timer is an Intel 8254 or compatible. There have been other ones introduced later but the 8254 should still be there, integrated into the chipset. Even Apple's computers now have one, ever since they switched to being (almost) PC-compatible.

kx5:

--- Quote from: kolbep on April 14, 2014, 01:12:29 pm ---Took a lot of searching, but I just found one in the wild....
--- End quote ---
Maximius Cmosinellidae?  :-\

ignator:
I saw one used in a timer for spraying from an aerosol can for room freshening. I think it was Glade brand.

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