Talk:Real-time clock

Question

What kind of clock is it physically? A crystal based clock or a "CPU cycle" clock speed clock? --Procrastinating@^talk2me 13:16, 4 October 2006 (UTC)

It's a battery backed crystal based clock, generally. BruceEwing 10:38, 19 November 2006 (UTC)

Philips microcontroller

Is there any reason that we're mentioning a specific Philips microcontroller on this page? I found a hastily written statement, which I edited and linked to the product page, but it seems somewhat overly-specific and out of place. --ThinkingInBinary 14:11, 6 March 2007 (UTC)

I have no idea, someone sorta left it there. I'm going to remove it. Codeczero 02:41, 24 August 2007 (UTC)

IRQ??

I think the fact that it associated with IRQ 8 should be mentioned. CPU MeltDown 14:09, 29 May 2007 (UTC)

references

the page now has several references, they aren't great, im not super fond of using application notes (although i did use 3 different manufacturers). if you can find better references feel free to replace mine Codeczero 02:30, 24 August 2007 (UTC)

How exactly does it work?

I have a strong impression that it is battery powered, but how exactly does it still precisely retain the right time when my system is off? By off I mean unplugged, computer packed in a box while moving to a new residence. Same thing with gameboys and other devices. I haven't really tried to remove the batteries for a couple months to see if the gameboy will still preserve the correct time, but I had my gameboy on the shelf untouched for 3 years with the same batteries, and it's fine. There must be some mechanical aspect in the technology that keeps it going.

So, how does it work?--Spectatorbot13 (talk) 21:34, 22 May 2009 (UTC)

Traditionally, the real-time clock in most computer devices is maintained by a tiny lithium rechargeable battery separate from the main power source of the computer or other device. In some newer devices, this is replaced by a modern capacitor that can hold a high charge, and is recharged every time the device is switched on.

I have a minor quibble; The PCs and electric power meters I have seen tend to use a lithium primary battery, usually a CR2032 (225mA-hours). It is not rechargeable. However, the power system usually only switches to it as a last resort. Most RTCs have a current draw of less than 1 microamp, so a 225mA/Hour CR2032 will run one for something like 10% less than 225,000 hours, i.e. over 22 years. The systems with two batteries tend to make one rechargeable. For the rechargeable they use either a supercap, which never degrades, or a nicad rechargeable derated, maybe even with a software charger algorithm, to get as many cycles as possible. Ray Van De Walker (talk) 21:32, 31 August 2021 (UTC)

Certainly designs have changed over the years so there are a lot of different ways this has been and is being done. Perhaps the article should not be so specific. ~Kvng (talk) 16:42, 4 September 2021 (UTC)