On 10/23/2022 at 6:42 PM, Edmond D said:
Given the changes in North America over my lifetime I'd hate to have daylight saving time in silicon, as it might break at some point. Especially given the move to eliminate it completely.
Daylight saving in silicon sucks. I found a x86-PC motherboard with an RTC chip I thought could be interesting to desolder and run standalone. So I thought it maybe had a daylight savings function.. but then for which country?;-) So I read the datasheet and found that it had a builtin automatic daylight savings function.. for a daylight savings that is obsolete. Luckily there's an option to use UTC.
(and running it separately is useful for being able to control the environment of the crystal so it can be made to provide very accurate time keeping)
On 10/23/2022 at 6:42 PM, Edmond D said:
In most industrial and scientific systems the clock is set to UTC so there is no confusion
That's the way to setup systems. The RTC chips usually adhere to rules that are outdated and irrelevant. But manufacturers stick with it. In fact it would be better if the RTC clock was a simple binary counter. That way all "smart" algorithms are moved into the operating system that can be updated with reasonable effort. Because even with a UTC mode setting. The operating system still usually have to re-calculate the date into a number of seconds since epoch, and then apply the local date rules anyway. And those re-calculations can make mistaken assumptions.
And even getting time zones and daylight savings right will not take account for leap seconds introduced in 1972 by ITU-R (or IERS?). And to make matters worse the daytime moves back-and-forth with a few ms over the decades.
On 10/23/2022 at 6:42 PM, Edmond D said:
Perhaps the X16 has a limitation in your view;
I doubt the X16 needs time zones or daylight savings. And anyway it can be implemented later in the kernal. In particular daylight savings might produce surprises.
But what is important is to know which behavior the system have so users know what they are dealing with and can expect. An X16 polyphonic alarm clock right now will fail on daylight savings dates unless accounted for in the code..
And the 60 Hz timer (jiffy?) will fail if the interrupt mechanism is not working properly. When a long NMI or IRQ disable occurs.