Sunday, 30 October 2016


Last night, the clocks went back.

I find this whole exercise of moving the clocks to and fro quite silly. But since everyone else is doing it, I have to.

Many of my clocks did it themselves - every computer, these days, knows about BST and adjusts itself without even telling you. And I have a radio-controlled clock which always sets itself correctly.  It wasn't always like that.

Back in 1984, 32 years ago, I had an IBM PC. And each time you started it up, it didn't know the date, let alone the time. It was January 1, 1980, and you had to tell it otherwise if you wanted your files datestamped correctly.

I had a little utility that I put in my autoexec, so that it ran each time I started up the computer. It read it's own file date and time, and assumed that the date and time was that, and I'd hit the up arrow to tell it that it was tomorrow.

Then the IBM AT had CMOS and a battery, so that once it knew the date and time, it knew it even after a reboot. But the PC clock wasn't an accurate clock, so it wandered off, gradually getting more and more distant from reality. People would say "I spent £1000 on this computer and it can't even keep good time!" Well, it can't make toast either. It's a computer, it's neither a clock nor a toaster.

When I started running Unix, I found out about ntp and time servers. If you do "rdate -s" then your system would reach out across the internet, and get the time from a public time server. I told one of my servers to do that once per day, and I told all my other servers to get the time from that server.

When I first got a Raspberry Pi, I found a familiar situation - it forgot the time each time it was powered up. You can get add-ons to fix that, but I just use my existing time server to get the date and time each time a Pi starts up.

So that's sorted for another six months.

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