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1993-08-11
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231 lines
====================================================== DSTIME
(c) Copyright 1993 Nathan Alan King
--------------------------------------------------- OVERVIEW
Daylight Saving Time (DST) provides more usable hours of
daylight for human activities by setting clocks ahead one
hour in the spring and back one hour in the fall. Although
the amount of actual daylight remains the same, more daylight
hours are available for outdoor work and recreation in the
late afternoon and evening. DST can also reduce the amount
of power used for lighting.
In most parts of the United States, year-round DST was
adopted during World War II. DST was extended during 1974
and 1975 because of the U.S. energy crisis. Now it is in
effect only during that part of the year when daylight hours
are the longest. Congress fixed this period as extending, as
of 1987, from the first (previously the last) Sunday in April
to the last Sunday in October. (These are the default
settings for DSTIME.)
Of course, Congress can change the standards at any time.
One proposed bill in Congress would have DST begin on the
third Sunday in March and end on the first Sunday in
November. The bill includes a provision to consider the
feasibility of advancing clocks an additional hour during the
summer months, for a total of four time changes a year:
advance an hour in early spring, advance another hour in
early summer, set back an hour in late summer, and set back
to Standard Time in late fall. With DSTIME you can handle
even such a complicated scheme; see MULTIPLE TIME SHIFTS
later in this manual.
The DSTIME program lets you leave your hardware clock in
Standard Time all year long while adjusting the DOS clock for
DST each time you turn on or boot your computer. DSTIME also
takes into consideration any logical future change in DST by
letting you change the settings used by the program.
DSTIME takes advantage of the fact that most IBM-compatibles
have both a hardware clock and a separate clock kept by the
operating system (DOS).
Every IBM-compatible computer beginning with the 80286-based
machines has a built-in, battery-powered clock that keeps
track of the time and date even when the computer is turned
off. In addition, many earlier compatibles are equipped with
add-on clock cards that accomplish the same thing. These are
"hardware" clocks. To change their settings you must use the
DOS SETUP program or the software that came with the clock
card.
DSTIME / Page 2
Every IBM-compatible computer runs a "system" (DOS) clock
that is set from the hardware clock when the computer is
turned on. Once the DOS time and date are set from the
hardware clock, DOS keeps its system clock running as long as
the computer is on. The time and date kept by DOS are used
by the operating system and the software you run on your
computer.
-------------------------------------- DSTIME in AUTOEXEC.BAT
Make sure that DSTIME with no parameters is in your
AUTOEXEC.BAT file after any calls to the hardware clock and
before any other programs are run. For example, your
AUTOEXEC.BAT file might look in part like this:
rem : set the dos prompt
PROMPT $P$G
rem : set dos clock from clock card
rem : (not necessary is '286 or higher machines)
AUTOTIME
DSTIME
rem : (other commands might follow in your AUTOEXEC.BAT)
---------------------------------------------- RUNNING DSTIME
DSTIME can be run in five ways, depending upon what you type
at the DOS command line. The five options are listed below.
DSTIME
DSTIME ?
DSTIME -
DSTIME +
DSTIME =
DSTIME
Running the program with a command of "DSTIME" with no
additional command-line parameters checks to see if the
current date and time are within the period of DST. If so,
the program sets the DOS clock ahead by appropriate number of
hours. (This will likely always be one hour, although you
can reset it in case Congress specifies a larger number of
hours.)
DSTIME ?
Running the program with a command of "DSTIME ?" displays two
help screens that tell you a bit about how to use the
program. The current DST settings are displayed as part of
the help screens. DSTIME makes no change to the DOS clock
when run in this way.
DSTIME / Page 3
DSTIME -
Running the program with a command of "DSTIME -" sets the DOS
clock back one hour regardless of whether the current date
and time are within DST. This option is included in case you
inadvertently run DSTIME more than once after you turn on
your computer. (You could also reboot to set DOS to the
proper time.)
DSTIME +
Running the program with a command of "DSTIME +" sets the DOS
clock back one hour regardless of whether the current date
and time are within DST. This option is included in case you
inadvertently run "DSTIME -" more times than necessary to
correct the DOS time. (You could also reboot to set DOS to
the proper time.)
DSTIME =
Running the program with a command of "DSTIME =" displays a
menu from which you can change the settings for DST. Use
this option only if Congress mandates new DST standards. The
current DST settings are displayed as you change settings so
you can see if you the new settings are correct. DSTIME
makes no change to the DOS clock when run in this way.
When you run DSTIME in this way, you see a main menu with the
following choices:
1 Set DST start date
2 Set DST end date
3 Set DST change time
4 Set DST time difference
5 Restore default settings
6 Finished - settings are correct
0 Quit without changing settings
Press the key of your choice (1-6,0).
The sub-menus are self-explanatory. Just follow the
instructions displayed on the screen.
---------------------------------------- MULTIPLE TIME SHIFTS
Should Congress decide to add an hour in the spring and again
in the early summer, and then set back an hour in the late
summer and the fall, DSTIME can still handle the changes.
To keep up with the changes you must have two copies of
DSTIME.EXE with different names, each with its own settings
for two of the time shifts.
DSTIME / Page 4
To make another copy, go to the directory where you keep
DSTIME.EXE, and then type the following command at the DOS
prompt:
COPY DSTIME.EXE DSTIME2.EXE
This will make a copy of the DSTIME program, but the new
copy's name will be DSTIME2.EXE. Now, run DSTIME in the
resetting mode by giving DOS the following command:
DSTIME =
Follow the menus and prompts to set DSTIME for the first and
last time shifts (early spring and late fall).
Run DSTIME2 in the resetting mode by giving DOS the following
command:
DSTIME2 =
Follow the menus and prompts to set DSTIME2 for the second
and third time shifts (early summer and late summer).
Make sure that DSTIME and DSTIME2 are in your AUTOEXEC.BAT
file after any calls to the hardware clock and before any
other programs are run.
DSTIME / Page 5
-------------------------------------------- SHAREWARE NOTICE
DSTIME (c) 1993 Nathan Alan King, All Rights Reserved
This program is released as shareware. If you find it useful,
please send a check or money order for $8.00 to:
Nathan Alan King
3928 Leafield Drive
Austin, TX 78749
You may copy and distribute this program provided you do not alter
it or charge for it. Your comments are welcome at the above
address or through CompuServe, User 72737,324.
Shareware by Nathan Alan King:
- FRETS, a computerized chord and key chart for guitar
- KEYPAD, a ten-key tutorial and practice program
- LOG, a simple project logging program
- STREAM, a version of LOG for writers
- TEXAS, a Lone Star Flag graphics program
Write for information about ScripTypist (tm), a non-shareware
program that makes screenplay pagination and printing a
pleasure instead of a chore.