BA23 Power Supply - test-drb@ccmp.vtda.org

25 Mar 2000

...
 One other thing remains. Most PDP11s have what's
called a 'line time 
clock' -- basically an interrupt every mains cycle. This is counted by 
the real time clock program in most OSes, and used to keep real time, 
etc. Of course if you move a machine from 60Hz to 50Hz power or vice 
versa, the real time clock will run slow/fast until you re-SYSGEN the OS 
for the appropriate frequency. This is not a big problem -- things still 
work -- though. 
Actually, the KDJ11-B based machines allowed any of the following
settings for the LTC interrupt rate:

	1) Line time clock (tied to power supply)
	2) 50 Hz
	3) 60 Hz
	4) 800 Hz

					Megan Gentry
					Former RT-11 Developer

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