[ont.micro.mac] Mac Clock

info-mac@utcsrgv.UUCP (info-mac) (06/19/84)

Date: 15 Jun 1984 12:56:52-EDT
From: uw-beaver!Robert.Aarhus@CMU-CS-SPICE
Subject: Mac Clock
To: utcsrgv!peterr
To: microsof!infomac


	I've discovered on my Mac that the interval for one second
	(Macsecond?) is not consistent - i.e. two seconds will pass
	on my wristwatch while only one passes for the Mac, then the
	Mac speeds up and catches up with itself. All in all, the
	clock is usually accurate with wristwatch time, unless you
	consider using it as a second timer.

info-mac@utcsrgv.UUCP (info-mac) (06/21/84)

Date: 19 Jun 84 16:10:08 PDT
From: uw-beaver!wert.pa@XEROX.ARPA
Subject: Re: Mac Clock
In-Reply-To: "Your message of 15 Jun 84 12:56:52 EDT"
To: Robert.Aarhus@CMU-CS-SPICE.ARPA
Cc: info-mac@SUMEX-AIM.ARPA

	I've discovered on my Mac that the interval for one second
	(Macsecond?) is not consistent - i.e. two seconds will pass
	on my wristwatch while only one passes for the Mac, then the
	Mac speeds up and catches up with itself. All in all, the
	clock is usually accurate with wristwatch time, unless you
	consider using it as a second timer.

This behavior is typical of all the Macs that I have seen. This is NOT
the clock speeding up or slowing down. When you think about it, that is
a silly idea. How could it ever work at all? What you are seeing is the
latency between when the clock changes and the display is updated. This
can be affected by any number of things, depending upon how busy the Mac
is at the moment, and whether it has to expand the heaps to do anything,
etc.

My Mac keeps time accurate to withing about 15 seconds a month, compared
to WWV. It only gets around to updating the clock display about every
1.5 seconds, thus making it appear that the clock jitters.

Scott