Tuesday, May 10, 2016

IRIS Date / Time

This page is a part of the "Understanding IRIS" collection.  Many thanks to David Takle, for figuring this out, and sharing this with us:


AUG 19, 1986  11:58:33 is the date that the IRIS OS gives when booted.

Where do you think that date might have come from?  

I'm wondering if it was the time that the original machine had as its current time from when this backup was made.  The date is close to what I would have expected.


That date would most likely be the backup date.
During shutdown, the system date is stored somewhere, probably in CONFIG, and picked up again during SIR (System Initialization Routine).

An interesting thing about IRIS dates .... The system has a base data somewhere, and then an hour counter from midnight on that date. Turns out the 65535 hours is about 7 and one half years, and then something needs to happen. In the original IRIS 4 that I worked with, we got a TRAP, and the date reset 7 years, or something like that. Maybe they fixed it later. But there is still a single 16-bit word holding hours since a base date. Not quite sure where we are right now.

You may have noticed that the clock is also FROZEN. The time never changes.
That's because we don't have any RTC -- real time clock -- running. There is one on LU0, but I have not tested it.
Incidentally, the frozen clock might be why we have not seen any Pico-N crashes! It might be waiting for some random number of minutes before doing its thing, and the time never comes.


This page is a part of the "Understanding IRIS" collection.  

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