\documentclass[letterpaper]{article}
\nonstopmode
\akai
\usepackage{linuxdoc-sgml}
\usepackage{qwertz}
\usepackage{url}
\usepackage[latin1]{inputenc}
\usepackage{t1enc}
\usepackage[english]{babel}
\usepackage{epsfig}
\usepackage{null}
\def\addbibtoc{
\addcontentsline{toc}{section}{\numberline{\mbox{}}\relax\bibname}
}%end-preamble
\setcounter{page}{1}
\title{¦p¦ó³]©w»Pºû«ù·Ç½Tªº¹q¸£®ÉÄÁ}
\author{§@ªÌ: Ron Bean, {\ttfamily \onlynameurl{rbean@execpc.com}}\\ 
Ä¶ªÌ: Da-Wei Chiang, {\ttfamily \onlynameurl{dawei@sinica.edu.tw}}}
\date{v, December 1996
Â½Ä¶¤é´Á: 2-16 July 1998}
\abstract{¦p¦ó³]©w»Pºû«ù·Ç½Tªº¹q¸£®ÉÄÁ.}


\begin{document}
\maketitle
\tableofcontents

\section{¤¶²Ð}

­Ó¤H¹q¸£(¬Æ¦Ü©ó©ù¶Qªº¤u§@¯¸)¥D¾÷ªO¤W©Ò¨Ï¥Îªº real-time-clock ´¹¤ù¤£°÷·Ç½T¬O²³©Ò¬Òª¾ªº¨Æ±¡. 
µM¦Ó Linux §@·~¨t²Î´£¨Ñ¤F¤@­ÓÂ²³æªº¤èªk¨Ó®Õ¥¿³o­Ó¤£·Ç½Tªº¹q¸£®ÉÄÁ, 
¨Ï±o¹q¸£®ÉÄÁ´Nºâ¬O¤£­Ê¿à¥~­±ªº®Õ®É·½¤]¥i¥H¹F¨ì *{\itshape ¬Û·í\/}* ·Ç½Tªº¦a¨B.
¦ý¬O¦ü¥G¤j¦h¼Æ¤H³£ÁÙ¤£ª¾¹D¦³³o­Ó¤èªk, ¨ä­ì¦]¦p¤U:

\begin{enumerate}
\item  ¦b¤@¯ë ``¦p¦ó³]©w linux §@·~¨t²Î'' ªº¤å¥ó¤¤¨Ã¥¼­z¤Î³o­Ó¤èªk,
¦Ó¥B¦b¦w¸Ë§@·~¨t²Î®É«ÜÃø¦Û°Ê¦a§¹¦¨³]©w (¦ý¬O²z½×¤W¨Ã¤£¬O¤£¥i¯àªº,
¦pªG§A¦³¤@¥x¼Æ¾Ú¾÷ªº¸Ü).
\item  ­Y§A¨Ï¥Î``{\ttfamily man clock}''¨Ó¬d¬Ý³]©w®ÉÄÁªº»¡©ú®É, 
§A¥i¯à·|¨ú±o«D¹w´Áªº {\ttfamily clock(3)} »¡©ú¤º®e.
(¸ÕµÛ¨Ï¥Î``{\ttfamily man 8 clock}'').
\item  ¦ü¥G¤j¦h¼Æ¤H¨Ã¤£¦b·N²{¦bªº¥¿½T®É¨è¬O¦h¤Ö.
\item  ¨º¨Ç¤Ö¼Æ¦b·Nªº¤H©¹©¹·|±Ä¥Î {\ttfamily louie.udel.edu} ©Ò´£¨Ñªº {\ttfamily xntpd} 
µ{¦¡¶°¥H«K»P¥~­±ªº®Õ®É·½, ¨Ò¦pºô¸ô®Õ®É¦øªA¾¹©ÎµL½u¹q®ÉÄÁ«H¸¹, ¨ú±o¦P¨B.
\end{enumerate}


¦pªG¦U¦ì¹ï¥»¤å©ÒÁ¿­zªº§C¶¥ªº®ÉÄÁ³]©w¤èªk¦³µÛ·¥°ª«×ªº¿³½ì,
§Ú±j¯P«ØÄ³¦U¦ìªá¨Ç®É¶¡¨ÓÂsÄýºô­¶\nameurl{http://www.eecis.udel.edu/ntp/}{} ,
³o­Óºô­¶¦³µÛ¦UÃþ§A©Ò·P¿³½ìªº¤º®e,¨Ò¦p¦³Ãö©ó {\ttfamily xntpd} ªº§¹¾ã¸ê°T¥H¤Î  NIST »P USNO µ¥¯¸¥xªº¶W³sµ². 
(§Ú¦b¥»¤å«á­±¤]¹ï {\ttfamily xntpd} §@¤F¨Ç³\ªºÂ²¤¶.)

\begin{description}
\item[ª`·N] \mbox{}

¦pªG§A¦b¦P¤@¥x¾÷¾¹¤W¶]¦h­Ó§@·~¨t²Î,
§AÀ³¸Ó¥uÅý¨ä¤¤¤@­Ó¨Ó­«·s³]©w CMOS ®ÉÄÁ,
¦p¦¹¥¦­ÌÅ×¤£·|¬Û¤¬¼vÅT¦Ó¾É­P²V¶Ã.
°²¨Ï§A¥­±`¦b¦P¤@¥x¾÷¾¹¤W¶] Linux ©M Windows ¤GºØ§@·~¨t²Î,
¦Ó·í§A­n´M§ä¤@¨Ç¦@¨Éªº®Õ®Éµ{¦¡«K®É¥i¥H©¿²¤ Windows §@·~¨t²Îªº³¡¤À
(°Ñ¦Ò«e­±©Ò»¡ºô­¶ªº¶W³sµ²).

\end{description}



\section{¨Ï¥Î``{\ttfamily clock}''µ{¦¡}

©Ò¦³§A¶·­nª¾¹Dªº¤º®e³£¦b {\ttfamily clock(8)} ªº»¡©ú¤¤,
¦Ó¥»¤å±N±a»â¦U¦ì§¹¦¨¾ã­Ó³]©wµ{§Ç.

\begin{description}
\item[ª`·N] \mbox{}

­n°õ¦æ``{\ttfamily clock}''©Î¬O¨ä¥¦·|¼vÅT¨ì¨t²Î®É¶¡©M CMOS ®ÉÄÁªºµ{¦¡,
§A¥²¶·¾Ö¦³ {\bfseries root} ªºÅv­­.

\end{description}



\subsection{ÀË¬d§Aªº§@·~¨t²Î}

ÀË¬d§A§@·~¨t²Îªº¶}¾÷°õ¦æÀÉ¤¤¬O§_¦³Ãþ¦ü``{\ttfamily clock -a}''©Î
``{\ttfamily clock -ua}''ªº©R¥O.
³o­Ó©R¥O¥i¯à©ñ¦b {\ttfamily /etc/rc.local} ,©Î {\ttfamily /etc/rc.d/rc.sysinit} ,
©Î¨ä¥¦Ãþ¦üªº¦a¤è, ³o­n¬Ý§A¦w¸Ëªº¬O¨º¤@®M Linux §@·~¨t²Î.

¦pªG§ä¨ìªº©R¥O¬O ``{\ttfamily clock -s}'' ©Î ``{\ttfamily clock -us}'' ,
½Ð±N ``{\ttfamily s}'' §ó§ï¦¨ ``{\ttfamily a}'' ,
±µµÛÀË¬d¬Ý¬Ý¬O§_¦³ {\ttfamily /etc/adjtime} ³o­ÓÀÉ®×,
¸ÓÀÉ®×ªº¤º®e¥u¦³¤@¦æ¬Ý°_¨Ó¹³¬O³o¼Ë:
\begin{tscreen}
\begin{verbatim}
0.000000 842214901 0.000000
\end{verbatim}
\end{tscreen}


³o¨Ç¼Æ¦r¨Ì§Ç¬O®Õ¥¿¦]¤l (¨C¤Ñ°¾®tªº¬í¼Æ),
¤W¤@¦¸®Õ¥¿®ÉÄÁªº®É¶¡ (¥Ñ Jan 1, 1970 ¶}©l°_ºâªº¬í¼Æ),
¤W¤@¦¸®Õ¥¿©Ò¦©°£ªº¬í¼Æ.
¦pªG§A§ä¤£¨ì³o­ÓÀÉ®×, ½Ð¥H {\bfseries root} ªº¨­¥÷²£¥Í¦¹ÀÉ®×,
¨ä¤º®e¥u¦³¤@¦æ¬Ý°_¨Ó¹³¬O³o¼Ë (¥þ³¡¬O¹s):
\begin{tscreen}
\begin{verbatim}
0.0 0 0.0
\end{verbatim}
\end{tscreen}


µM«á³z¹L shell ¤â°Ê°õ¦æ ``{\ttfamily clock -a}'' ©Î ``{\ttfamily clock -ua}''
¥H«K§ó·s²Ä¤G­Ó¼Æ¦r
(¦pªG§Aªº®ÉÄÁ³Q³]©w¦¨¨ó½Õ°ê»Ú®É¶¡¦Ó¤£¬O¥»¦a®É¶¡
§A±o¨Ï¥Î ``{\ttfamily u}''³o­Ó°Ñ¼Æ).


\subsection{¶q´ú®ÉÄÁªº°¾®t²v}

­º¥ý§A±oª¾¹D²{¦b¨ì©³¬O´XÂIÄÁ {\ttfamily :-)}.
§A¾÷¾¹ªº¥»¦a®É¶¡¥i¯à¬O¤£·Ç½Tªº.
§Ú³Ì³ßÅwªº¤èªk¬O¼·¹q¸Ü¨ì WWV ªº (303)499-7111 ¹q¸Ü³ø®É¥x
(³o¬O­Ó¥I¶O¹q¸Ü).
¦pªG§A¯à°÷»Pºô¸ô®Õ®É¦øªA¾¹³s¤W½u,
§A¤]¥i¥H¨Ï¥Î {\ttfamily xntpd} µ{¦¡¶°©Ò´£¨Ñªº {\ttfamily ntpdate} µ{¦¡¨Ó®Õ®É
(¨Ï¥Î {\ttfamily -b} ¿ï¶µ¥HÁ×§K¨t²Î§Ë¶Ã CMOS ®ÉÄÁ).
©ÎªÌ¨Ï¥Î ``{\ttfamily date -s hh:mm:ss}'' ¥H¤â°Ê¤è¦¡³]©w¨t²Î®ÉÄÁ,
¤£½×¨º¤@ºØ¤èªk³Ì«á³£±o¨Ï¥Î ``{\ttfamily clock -w}'' ±N¨t²Î®É¶¡¼g¤J CMOS ®ÉÄÁ.
§A¥²¶·°O±o³Ì«á¤@¦¸³]©w®ÉÄÁªº¤é´Á,
©Ò¥H§A±o±N¸Ó¤é´Á¼g¤U¨Ó©ñ¦b¤£·|¿ò¥¢ªº¦a¤è.
¦pªG§A¨Ï¥Îªº¬O {\ttfamily ntpdate} µ{¦¡, °õ¦æ ``{\ttfamily date +\%s}''
µM«á¼g¤U¦Û±q Jan 1,1970 ºâ°_¨ì¸Óµ{¦¡°õ¦æªº¬í¼Æ.

µM«áµ¥«Ý´X¤Ñ©Î´X­Ó¬P´Á«á¤§«á¦A¦^¨Ó¬Ý¬Ý®ÉÄÁ¨ì©³°¾®t¤F¦h¤Ö®É¶¡.
¦pªG§A¥H¤â°Êªº¤è¦¡³]©w®ÉÄÁ, «ØÄ³¦Ü¤Ö±oµ¥«Ý¤G­Ó¬P´Á¤§«á,
¦A¨Ó­pºâ®ÉÄÁ°¾®t²v±N¥i±o¨ìÁÍªñ .1 sec/day ªºµ²ªG.
´X­Ó¤ë¤§«á°¾®t²vÀ³¸Ó·|ÁÍªñ  .01 sec/day
(¦³¨Ç¤H«ÅºÙÀ³¸Ó§ó·Ç½T, ¦ý¬O§Ú­Ó¤H«ù«O¯dªººA«×).
¦pªG§A¨Ï¥Î {\ttfamily ntpdate} µ{¦¡¨Ó³]©w®ÉÄÁ§A¥i¯à¤£¥²µ¥«Ý¤Ó¤[ªº®É¶¡,
µM¦Ó¤£½×¨Ï¥Î¨ººØ¤è¦¡¤§«á³£±o°µ¨Ç·L½Õªº¤u§@.

§A¥i¥H¨Ï¥Î cron ¦b¤@©wªº®É¶¡©P´Á¤º°õ¦æ ``{\ttfamily clock -a}''
¥H«K¨t²Î®É¶¡¯à°÷»P (®Õ¥¿¹Lªº) CMOS®É¶¡ºû«ù¤@­P©Ê.
¨ä¹ê¦b§A¨C¦¸¶}¾÷ªº®É­Ô³£·|±q¶}¾÷°õ¦æÀÉ¨Ó°õ¦æ³o­Ó©R¥O,
µM¦Ó¥u­n±`±`°µ¤W­±³o­Ó°Ê§@´N¥i¥H¹F¨ì§A·Ç½T¾÷¾¹®É¶¡ªº¥Øªº. 

ª`·N¦pªG¨t²Î®É¶¡ªº­×¥¿¤@¦¸¶W¹L¤@¬í©Î¬O®É¶¡©¹¦^­×¥¿,
¦³¨Ç¨t²Îªº clock µ{¦¡¥i¯à·|µLªk°õ¦æ.
¦pªG§A¦³³o¤è­±ªº°ÝÃD, «h¥i¥H¨Ï¥Î {\ttfamily xntpd} ©Î {\ttfamily ntpdate} µ{¦¡
¨Ó³v¨B¦a­×¥¿®É¶¡. 


\subsection{¹ê¨Ò}


\subsubsection{³]©w®É¶¡}

Ã±¤J¨t²Î¨Ã¦¨¬° {\bfseries root}.
¼·¹q¸Ü¦Ü (303)499-7111 (»y­µ), ¨Ó²âÅ¥³ø®Éªº¤º®e.
µM«á¨Ï¥ÎÁä½L¥´¥X¤U­±´X­Ó¦r:
\begin{tscreen}
\begin{verbatim}
date -s hh:mm:ss
\end{verbatim}
\end{tscreen}

¤@ª½µ¥¨ì¹Íªº¤@ÁnÅ×«ö¤U enter Áä.
(¦pªG¦b¦¹³B¨Ï¥Î ``{\ttfamily ntpdate}'' µ{¦¡, «h§A¥i¥H¬Ù²¤¼·¹q¸Üªº°Ê§@)
³o­Ó¨BÆJ¦b³]©w ``¨t²Î®É¶¡''.
±µµÛ°õ¦æ:
\begin{tscreen}
\begin{verbatim}
clock -w
\end{verbatim}
\end{tscreen}

³o­Ó¨BÆJ±N¨t²Î®É¶¡¼g¦^ CMOS ®ÉÄÁÅý¤GªÌ®É¶¡¤@­P.
±µµÛ°õ¦æ:
\begin{tscreen}
\begin{verbatim}
date +%j
\end{verbatim}
\end{tscreen}

(¦pªG¦b«e­±¨Ï¥Î ``{\ttfamily ntpdate}'' µ{¦¡§A±o°õ¦æ ``{\ttfamily date +\%s}'')
±N¨ä°õ¦æªºµ²ªG°O¿ý¤U¨Ó.


\subsubsection{­«·s³]©w®É¶¡»PÀË¬d°¾®t²v}

§ä¥X§A¤W¦¸¼g¤U¨Ó¤é´Á.
Ã±¤J¨t²Î¨Ã¦¨¬° {\bfseries root}.
µM«á°õ¦æ:
\begin{tscreen}
\begin{verbatim}
clock -a
\end{verbatim}
\end{tscreen}

³o­Ó¨BÆJ±N CMOS ®É¶¡¼g¤J¨t²Î®ÉÄÁÅý¤GªÌ®É¶¡¤@­P.
¼·¹q¸Ü¦Ü (303)499-7111 (»y­µ), ¨Ó²âÅ¥³ø®Éªº¤º®e.
±µµÛ¨Ï¥ÎÁä½L¥´¥X¤U­±´X­Ó¦r:
\begin{tscreen}
\begin{verbatim}
date
\end{verbatim}
\end{tscreen}

¤@ª½µ¥¨ì¹Íªº¤@ÁnÅ×«ö¤U enter Áä, ¦ý¬O·í§Aµ¥«Ýªº®É­Ô, ¼g¤U³ø®Éªº¤º®e,
¨Ã¥BÁÙ¤£­n±¾¤W¹q¸Ü.
³o­Ó°Ê§@¬OÅý§Aª¾¹D¥Ø«e¯u¥¿ªº®É¶¡¬O´XÂI,
¦Ó¦¹®É¬Û¹ï§Aªº¾÷¾¹¤Wªº®É¶¡¬O´XÂI.
²{¦b¨Ï¥ÎÁä½L¥´¥X¤U­±´X­Ó¦r:
\begin{tscreen}
\begin{verbatim}
date -s hh:mm:00
\end{verbatim}
\end{tscreen}

¨ä¤¤¤À°w³¡¤À©Ò³]©wªº¼Æ¦r´N¬O¥Ø«e³ø®É¤º®e *{\bfseries ¤§«áªº}* ¤U¤@¤ÀÄÁ,
¤@ª½µ¥¨ì¹Íªº¤@ÁnÅ×«ö¤U enter Áä (²{¦b¥i¥H±¾¤W¹q¸Ü¤F).
¦Ó {\ttfamily hh} ªº³¡¤À«h¨Ï¥Î¾÷¾¹¥»¦aªº®É°w¼Æ¦r§Y¥i.
³o­Ó¨BÆJ¦b³]©w ``¨t²Î®É¶¡''.
µM«á°õ¦æ:
\begin{tscreen}
\begin{verbatim}
clock -w
\end{verbatim}
\end{tscreen}

±N·sªº (®Õ¥¿¹Lªº) ¨t²Î®É¶¡¼g¦^ CMOS ®ÉÄÁ. 
µM«á°õ¦æ:
\begin{tscreen}
\begin{verbatim}
date +%j
\end{verbatim}
\end{tscreen}

(©Î¬O°õ¦æ ``{\ttfamily date +\%s}'' )

§A²{¦b¤â¤W¦³¤T­Ó¼Æ¦r (¤G­Ó®Õ¥¿¤é´Á¤Î¤@­Ó¥¿½T®É¶¡)
©ó¬O§A¥i¥H¶}©l­pºâ°¾®t²v¤F.


\subsubsection{­pºâ®Õ¥¿¦]¤l}

·í§A¦b¬Y¤@¤ÀÄÁ°õ¦æ ``{\ttfamily date}'' µ{¦¡®É, §A¾÷¾¹ªº¥»¦a®É¶¡¬OºCÁÙ¬O§Ö©O?
¦pªG¬O§Ö¤F, §A¥²¶·±N¤§´î¥h¤@¨Ç¬í¼Æ¥H²Å¦X¥¿½T®É¶¡,
©Ò¥H§AÀ³¸Ó¼g¤U¤@­Ó­tªº°¾®t¼Æ­È.
¦pªG¬OºC¤F,§A¥²¶·±N¤§¥[¤W¤@¨Ç¬í¼Æ¥H²Å¦X¥¿½T®É¶¡, ©Ò¥H§AÀ³¸Ó¼g¤U¤@­Ó¥¿ªº°¾®t¼Æ­È.

²{¦b±N¤G­Ó®Õ¥¿¤é´Á¬Û´î.
¦pªG¤§«e§A¨Ï¥Îªº¬O ``{\ttfamily date +\%j}'',
«h¼Æ­È©Ò¥Nªí·N¸q¬°¤@¦~ªº²Ä´X¤Ñ (1-365, ©Î 1-366 ¦pªG¬O¶|¦~).
¦pªG¦Û±q§A¤W¤@¦¸³]©w®ÉÄÁ¨ì²{¦b¸g¹L1 ¤ë1 ¤é§AÁÙ¶·­n±N²Ä¤G­Ó®Õ¥¿¤é´Á¥[ 365 (©Î 366)
¦pªG¤§«e§A¨Ï¥Îªº¬O ``{\ttfamily date +\%s}'' «h¼Æ­Èªº³æ¦ì¬°¬í¼Æ,
§A¥²¶·±N¤§°£¥H 86400 ¥H«K¨ú±o¤é¼Æ.

¦pªG§AªºÀÉ®× {\ttfamily /etc/adjtime} ¤¤¤w¸g¦³®Õ¥¿¦]¤l,
§A¥²¶·±N¥ý«e¤w®Õ¥¿¹Lªº¬í¼Æ¦Ò¼{¶i¨Ó,
¦pªG§A®Õ¥¿¹L«×, ³o­Ó®Õ¥¿¦]¤lªº¥¿­t¸¹±N»P§A¶q´ú¨ì°¾®t¼Æ­È¬Û¤Ï; 
¦pªG§A®Õ¥¿¤£¨¬«h¤GªÌ¥¿­t¸¹¬Û¦P.
±NÂÂªº®Õ¥¿¦]¤l­¼¥H¤é¼Æ,
µM«á¥[¤W·sÀò±oªº°¾®t¬í¼Æ
(ªþµù--
¦pªG¤GªÌ¥¿­t¸¹¬Û¦P, §A±N¨ú±o¤@­Ó¸û¤jªº°¾®t¼Æ­È,
¦pªG¤GªÌ¥¿­t¸¹¬Û¤Ï, §A±N¨ú±o¤@­Ó¸û¤pªº°¾®t¼Æ­È).

±µµÛ±N³o­ÓÁ`°¾®t¬í¼Æ°£¥H¤é¼Æ¥H«K¨ú±o·sªº®Õ¥¿¦]¤l,
µM«á±NÀÉ®× {\ttfamily /etc/adjtime} ¤¤ÂÂªº®Õ¥¿¦]¤l¥N´«¦¨·sªº.
³Ì«á¼g¤U·sªº®Õ¥¿¤é´Á (¥H¬í¼Æ©Î¤é¼Æ¬°³æ¦ì) ¥H«K¤U¦¸¨Ï¥Î. 

³o¸Ì¬O§Úªº {\ttfamily /etc/adjtime} ÀÉ®×¤º®e:
\begin{tscreen}
\begin{verbatim}
-9.600000 845082716 -0.250655
\end{verbatim}
\end{tscreen}

(ª`·N¨C¤Ñ 9.6 ¬í«h¤@­Ó¤ë±Nªñ¦³ 5 ¤ÀÄÁªº°¾®t!)






\section{xntpd Â²¤¶}

§Aªº¨t²Î¹ê»Ú¤W¦³¤G­Ó®ÉÄÁ-- ¤@­Ó¬O·í¨t²ÎÃö¾÷Ä~Äò¨Ï¥Î¹q¦À¹q¤Oºû«ù­p®É¥\¯àªº 
``real time clock'' (¤]´N¬O©Ò¿×ªº ``CMOS ®ÉÄÁ'', ``µwÅé®ÉÄÁ'', ©Î ``RTC'')
¦Ó¥t¤@­Ó¬O ``kernel clock'' (¦³®ÉºÙ¬° ``³nÅé®ÉÄÁ'' ©Î ``¨t²Î®ÉÄÁ'')
¨t²Î®ÉÄÁªº¸õ°Ê¬O¥H­p®É¾¹ªº¤¤Â_«H¸¹¬°°ò·Ç¨Ã¦b¶}¾÷®É±qCMOS ®ÉÄÁ³B¸ü¤Jªì©l­È.
³o¤G­Ó®ÉÄÁ¦³¤£¦Pªº®É¶¡°¾®t²v,
©Ò¥H¤G­Ó®ÉÄÁ¤Wªº®É¶¡·|³vº¥¦a²£¥Í°¾®t,
¦Ó¥B¤]·|»P ``¯u¥¿ªº''®É¶¡²£¥Í°¾®t.

¦b {\ttfamily xntpd} ¤å¥ó¤¤©Ò­z¤Îªº ``the clock'' ´N¬O«ü ``kernel clock''.
·í§A°õ¦æ {\ttfamily xntpd} ©Î {\ttfamily timed} µ{¦¡®É
(©Î¬O¨ä¥L¨Ï¥Î¨ì {\ttfamily adjtimex} ¨t²Î©I¥sªºµ{¦¡)
linux §@·~¨t²Î·|°²©w¨t²Î®ÉÄÁ¤ñ CMOS ®ÉÄÁ·Ç½T,
¦Ó¥B·|¦b¶}¾÷«á¨C¹j 11 ¤ÀÄÁ­«·s³]©w¤@¦¸ CMOS ®É¶¡ (¤@ª½¨ì­«¶}¾÷¬°¤î).
³o·N¨ýµÛ ``{\ttfamily clock}'' µ{¦¡¤£¦Aª¾¹D¤W¤@¦¸­«·s³]©w CMOS ®ÉÄÁªº¥¿½T®É¶¡,
©Ò¥H§A¤£¥i¥H¨Ï¥ÎÀÉ®× {\ttfamily /etc/adjtime} ¤¤ªº®Õ¥¿¦]¤l.
§A¥i¥H¦b¶}¾÷°õ¦æÀÉ¤W¨Ï¥Î {\ttfamily ntpdate} µ{¦¡
¥H«K¦bªì¦¸°õ¦æ {\ttfamily xntpd} µ{¦¡¤§«e»P®Õ®É¦øªA¾¹¹ï®É.
¦pªG§A¦b¶}¾÷ªº®É­Ô¤@ª½µLªk³s¤W·Ç½Tªº®Õ®É·½, ³o¥i¯à·|Åý§A­±Á{¨ì¤@¨Ç§x¹Ò--
¹ê»Ú¤W {\ttfamily xntpd} ¤£¬O³Q³]­p¨Ó¦b¨ººØ±¡ªp¤§¤U¨Ï¥Îªº.

{\ttfamily Xntpd} ¥]§t¤F³\¦hµL½u¹q®ÉÄÁªºÅX°Êµ{¦¡,
¨Ã¥B¤]¥i¥H³Q³]©w¦b¤@©wªº©P´Á¤º¼·¹q¸Ü¦Ü NIST ªº¹q¸Ü¼·±µ¹q¸£®Õ®ÉªA°È
(·í§A³]©w¦n¹q¸Ü¼·±µªº©P´Á¤§«á³Ì¦n¥ý­pºâ¤@¤U¹q¸Ü±b³æªºªá¶O).
¦b»P¨ä¥Lªº®Õ®É·½¥¢¥hÁpµ¸¤@¬q®É¶¡¤§«á³o­Ó¤è¦¡¤]¯à´£¨Ñ¨t²Î®ÉÄÁ¤@­Ó®Õ¥¿¦]¤l.

¤j³¡¤ÀªºµL½u¹q®ÉÄÁ¤j¬ù­nªá¶O \$3-4K,
¤£¹L§A¥i¥H±Ä¥Î¸û«K©yªº ``{\ttfamily gadget box}'' ¤è®×
(¹ê»Ú¤W¬O¤@­Ó 300 baud ªº¼Æ¾Ú¾÷) ¥L³Q©ñ¦b§Aªº¹q¸£»P¤@¥xµuªiµL½u¹q±µ¦¬¾¹¤§¶¡
ÀW¹D½Õ¦Ü Canada ªº CHU ®Õ®ÉµL½u¹q¥x
(°Ñ¨£ºô§} \nameurl{ftp://ftp.udel.edu/pub/ntp/gadget.tar.Z}{}).
¦ÓHeathkit WWV ±µ¦¬¾¹ (``³Ì·Ç½Tªº®ÉÄÁ'')
¤´µM¶Rªº¨ì (¦ý¤£¬O¤@²Õ®M¥ó), ¤j¬ù­nªá¶O \$4-500.
¥Ø«eGPS ªº°T¸¹¸Ì¤´µM¥]§t¦³®Õ®Éªº¸ê°T,
¦Ó¥B³¡¤Àªº GPS ±µ¦¬¾¹¥i¥H±µ¤W¹q¸£ªº¦ê¦C°ð.
¦b³Ìªñªº¥¼¨Ó³o¥i¯à·|¦¨¬°§C»ù¦ìªº¸Ñ¨M¤è®×.

²z½×¤W, ¤@¯ë¤H¥i¥H¦Û¤v¼gµ{¦¡¨Ó¨Ï¥Î NIST ªº¹q¸Ü¼·±µ¹q¸£®Õ®ÉªA°È¥H«K¦Û°Ê
­pºâ CMOS ®ÉÄÁ»P¨t²Î®ÉÄÁªº°¾®t²v.
ÁöµM§Ú¤£ª¾¹D¬O§_¦³³æ¿Wªºµ{¦¡¯à°÷¹F¨ì³o­Ó¥Øªº,
¦ý¬O¤j³¡¤Àªºµ{¦¡½XÀ³¸Ó¥i¥H­É¥Î¦Û {\ttfamily xntpd} µ{¦¡¶°.

\end{document}
