bjork@NISC.SRI.COM (Steve Bjork) (07/25/90)
Well, the clock crystal is different from the CPU crystal. The older suns have the battery needed to keep the date clock alive in power off situations, implying the CPU clock being off. The clock chip crystal is much lower frequency than the CPU crystal, since more power is used at higher frequencies. I think the typical clock chip crystal frequency is 32,768 Hertz. So any coders out there might want to have a couple things to check--one being the time of day read from the clock chip, another perhaps equivalent to a timer (like in the 9513 chip) set and read by a software driver, the timer being clocked by the CPU crystal. I know the Multibus and VMEbus sun2's were like this; some of the sun 3's were also. The newer stuff I haven't had too much chance to hack on, so I'm not sure about them. --Steven