According to Christopher Tidy :
Too_Many_Tools wrote:

snip

While I have not seen the time keeping circuitry of a SUN station, I
would wager that they had a small oven for the oscillator that kept the
quartz crystal at a stable temperature.

Out of curiosity I downloaded the data sheet for the "Timekeeper RAM"
M48T59Y chip. It is quite a sophisticated device. Frequency accuracy is
better than ~20 ppm between 0 deg. C and 50 deg. C. That equates to a
maximum error of about 50 seconds per month. It also incorporates a
calibration feature through which the clock can be speeded up or slowed
down according to a 5-bit number loaded into a register. This apparently
brings the accuracy to within 2 ppm at 25 deg. C. It's a neat device. I
guess you get what you pay for - you don't find a £20 clock chip on a
£50 motherboard. Whether Sun use the calibration feature on the chip I
don't know. If anyone knows please let me know. I'm curious.

Among the options to the "date" command, which can both read
and display the date, and set it, is:

================================================== ====================
-a [-]sss.fff Slowly adjust the time by sss.fff seconds
(fff represents fractions of a second). This
adjustment can be positive or negative. The
system's clock is sped up or slowed down
until it has drifted by the number of
seconds specified. Only the super-user may
adjust the time.
================================================== ====================

So -- yes, Sun does use the speed control.

This is from the man page to Solaris 10. But the same is in the
man page for "date" for Solaris 2.6 ("Solaris 10" should be "Solaris
2.10", if they had not changed the naming rules somewhere between 2.6
and 2.9. I don't have Solaris 8 (or is it Solaris 2.8?) to check
whether that was where the change was made.

Enjoy,
DoN.
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