First the author's description, then the quickstart guide
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CLOCK consists of two programs that give you complete control over the
operation of your calendar (battery-protected) clock and your DOS/BIOS
internal timer. The normal DOS mode of operation is to read the calendar
clock when you boot the system and set the internal timer. Thereafter all
read operations refer only to the internal timer while time setting operations
write to both clocks.
Some of the drawbacks to the standard DOS clock operation that the CLOCK
programs address are:
o There is no provision to switch time zones without resetting the
system time.
o DOS does not handle automatic changes between daylight savings time
and standard time.
o The DOS/BIOS internal timer often drifts quite rapidly away from the
time maintained by the more accurate calendar clock.
o Even the calendar clock drifts slowly away from the accurate time.
DOS provides no way to automatically adjust for that drift.
o If your battery is failing or some other hardware or software
problem messes up the time in your calendar clock, there is no way
to detect that except by manually displaying the time and checking
it.
o The standard DOS and BIOS software on some PCs can miss the change
to a new day when the PC is left on over midnight.
o Your clock might not handle automatic changes to a new year or may
not understand leap years.
If any of those circumstances cause problems for you, CLOCK can help. The two
primary programs are CLOCK.SYS and CLK.EXE.
CLOCK.SYS is a clock device driver (CLOCK$ device). It replaces the
DOS internal clock driver. CLOCK.SYS provides for automatic time
zone conversion. It also allows you to periodically or continuously
get the time from the calendar clock. This can totally eliminate
problems with missing day changes and realtime clocks that are
inaccurate.
CLK.EXE is a program that allows you to separately control your
DOS/BIOS internal clock and battery-protected calendar clock. Most
importantly, CLK.EXE will handle time zones and will automatically
switch between standard and daylight savings time for you. It also
supports automatic adjustment for calendar clock drift, checks for
incorrect or unlikely times, and can restrict time changes.
CLOCK consists of two programs that give you complete control over the
operation of your calendar (battery-protected) clock and your DOS/BIOS
internal timer. The normal DOS mode of operation is to read the calendar
clock when you boot the system and set the internal timer. Thereafter all
read operations refer only to the internal timer while time setting operations
write to both clocks. In levels of DOS prior to 3.3, even time setting opera-
tions only wrote to the internal timer. In order to set the calendar clock
you had to run the SETUP program.
Some of the drawbacks to the standard DOS clock operation that the CLOCK
programs address are:
o There is no provision to switch time zones without resetting the
system time.
o DOS does not handle automatic changes between daylight savings time
and standard time.
o The DOS/BIOS internal timer often drifts quite rapidly away from the
time maintained by the more accurate calendar clock.
o Even the calendar clock drifts slowly away from the accurate time.
DOS provides no way to automatically adjust for that drift.
o If your battery is failing or some other hardware or software
problem messes up the time in your calendar clock, there is no way
to detect that except by manually displaying the time and checking
it.
o If you have to run a program that occasionally changes the time
incorrectly, there is no way to protect your clock from those
changes. You can also have this problem if you are a parent whose
children set the clock when you don't want them to, an instructor
whose students reset the time, or an expert young user whose parents
mess up your clock.
o If you need to experiment with special times and dates but don't
want to have to reset your clock afterwards, DOS has no mechanism to
h e l p. In order to test end-of-month processing for your
application, you have to set the date and time, run your tests, and
then set the time and date back.
o The standard DOS and BIOS software on some PCs can miss the change
to a new day when the PC is left on over midnight.
o Your clock might not handle automatic changes to a new year or may
not understand leap years.
o You may have an older PC from before the PC/AT clock standardization
and your vendor no longer releases new versions of DOS for that PC.
You are stuck on DOS 3.2 or earlier or you have to give up your
calendar clock.
If any of those circumstances cause problems for you, CLOCK can help. The two
primary programs are CLOCK.SYS and CLK.EXE. In addition, if you are a
software developer, CLKDEMO is provided in source code to show you how to
program the extended clock operations into your own applications.
CLOCK.SYS is a clock device driver (CLOCK$ device). It replaces the
DOS internal clock driver. CLOCK.SYS provides for automatic time
zone conversion. It also allows you to periodically or continuously
get the time from the calendar clock. This can totally eliminate
problems with missing day changes and realtime clocks that are
inaccurate. CLOCK.SYS provides support for many types of calendar
clocks including many of the original add-in clocks of the 8088 era.
If your clock is not currently supported, I want to hear from you.
I will be happy to add it to the software.
CLK.EXE is a program that allows you to separately control your
DOS/BIOS internal clock and battery-protected calendar clock. Most
importantly, CLK.EXE will handle time zones and will automatically
switch between standard and daylight savings time for you. It also
supports automatic adjustment for calendar clock drift, checks for
incorrect or unlikely times, and can restrict time changes.
CLKDEMO.EXE is a small part of CLK.EXE that is provided in source
code (C language) form so that you can see how to add clock control
to your own applications.
The latest version of CLOCK (3.81) has the option to automatically set two
DOS environmental variables ("TZ" and "GTZ").
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QUICKSTART GUIDE
Since nobody reads instructions, this is the quickstart guide:
1. Move CLOCKnnn.EXE to a directory, and execute the file to unpack
the contents (it's a self-extracting archive).
2. Optionally move CLOCK.SYS, CLK.EXE, and CLK.INI to better directories.
It is useful for CLK.EXE to be in a directory which is in the PATH,
and it is easier if CLK.INI is in the same directory as CLK.EXE
3. Edit CLK.INI to add two lines below . The first specifies the timezone
rules, and the second enables auto-setting of the 'TZ' and 'GTZ'
environment variables. The first line is country dependant - I'm
assuming readers are in the U.K.:
TZ=GMT0BST,M3.5.0/1,M10.5.0/2
/T
4. In CONFIG.SYS, add the line:
DEVICEHIGH=<path>\CLOCK.SYS
This syntax assumes the use of EMM386 : QEMM users, for example, will
need a different syntax.
5. In AUTOEXEC.BAT, as early in the file as practical, add the line:
<path>\CLK /I
6. If you use Windows, edit the SYSTEM.INI file. Find the line that
looks like:
[386Enh]
Immediately after that line (or anywhere in the [386Enh] section),
add the line
SyncTime=false
7. Reboot the machine. You should see CLOCK.SYS announce itself as
CONFIG.SYS is processed, and see a multi-line message from CLK.EXE
as AUTOEXEC.BAT is processed.
8. Use the DOS 'TIME' command (or another clock setting program) to set
the clock as accurately as possible. Note that DOS will probably offer
the wrong time just this once, as your CMOS clock is now assumed to be
on GMT.
9. Use the 'CLK' command (hence recommending it be in the path) to check
on the clock status. The current timezone name and offset should be given,
together with the values of the CMOS clock (which should be on GMT) and
the DOS clock (which should be on local time).
10. Use the 'SET' command to look at environmental variables. 'TZ' and 'GTZ'
should both be set. 'TZ' should be a short value (e.g. 'GMT0', 'BST-1')
and 'GTZ' should look similar to the 'TZ=' statement in CLK.INI
11. Give the machine some time, perhaps 2 weeks or a month, until the time
(perhaps as reported by 'CLK') has drifted off by a fair number of
seconds. Reset the clock (with 'TIME' or whatever) as accurately as
possible, and immediately enter the command:
CLK M=LAST
This will store a correction history line in CLK.INI
12. After another similar interval, repeat step 11. This time, the screen
output from the 'CLK' command will include a calculated correction
factor.
13. Depending on your patience, repeat step 12 a number of times, until the
displayed calculated correction value stays fairly constant.
14. When you're happy, after doing a 'CLK M=LAST' command, follow it
with the command:
CLK A=M
This will clear the correction history lines in CLK.INI, and add
a line specifying the correction factor to apply.
ADS Benham, G8FSL
15 April 1996
