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The PC-SIG Library 10
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The PC-Sig Library - Shareware for the IBM PC and Compatibles (PC-SIG)(Tenth Edition Disks 1-2804)(1991).iso
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PC_SIGCD
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DISK1127.ZIP
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WCD50ZIP.EXE
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WCD50.DOC
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1989-11-13
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************************************************************
* *
* W O R L D C I T Y *
* D I S T A N C E C O M P U T E R *
* *
* WCD Version 5.0 *
* *
* (C)opyright 1989 *
* All Rights Reserved *
* *
*==========================================================*
* *
* GeoGraphics Software *
* 126 Mountain View Road *
* Glastonbury, CT 06033 *
* *
*----------------------------------------------------------*
* *
* WCD is user-supported software provided to *
* you at no charge on a trial basis. If you use this *
* software and find it of value please register your *
* copy for $15.00 and support the shareware concept. *
* Registered users will be provided with information *
* about program updates. Please make checks payable *
* to G. K. Marek at the above address. *
* *
* You are encouraged to share this software with *
* others provided that it is distributed complete *
* with documentation and in unmodified form, and *
* that no fee or other consideration is charged or *
* accepted. All commercial, business and government *
* users must register each copy in use. *
* *
* We hope you enjoy using WCD. Your comments and *
* suggestions to improve this product are always welcome. *
* *
* *
* November 1989 *
************************************************************
PROGRAM DESCRIPTION
WCD, The World City Distance Computer, is designed to provide distance
and travel time information between over 700 different world cities,
including most major US cities. It allows input of user specified
locations. Flight times account for estimated enroute winds. The
program is windowed and menu driven, and contains location search
capabilities.
HARDWARE REQUIREMENTS
This program is designed for IBM Personal Computers and close
compatibles. It will execute on the IBM-PC, PC-XT, PC-jr, and on
compatible 286 and 386 machines. DOS Version 2.1 or later is required.
Since the program relies extensively on color, a color monitor is
recommended. The program will run, however, unmodified, on the Compaq
or Toshiba. WCD requires about 75K of memory and does not require BASIC
to operate.
PROGRAM INFORMATION
The program is started by issuing WCD at the DOS prompt. You will see
the program loading city information from its built-in database of 200+
plus US cities. It will also load in city data from a separate datafile
that the user can alter. More about this in the DATAFILE section.
Menu instructions appear on the left and a window of city information
appears on the right. Locations are identified by a three character
code which represents that city's airport code. Most large cities use
three letter codes such as ORD for Chicago's O'Hare Airport, but smaller
cities may use a combination of letters and numbers. Some cities have
several airports in the database. If the desired city code is known it
can simply be entered at the keyboard. If the code is not known, the
window on the right can be used to relate the codes to the respective
cities. Use the scroll keys to search this window for the three
character code of the city desired, including the Up/Down Arrows,
PageUp, PageDown, Home and End keys. Pressing [Enter] will select the
city highlighted in the window.
The function keys [F1] - [F9] provide functions to assist in specifying
your desired city pairs including a database search function. See the
FUNCTION KEY section for detailed description.
PROGRAM FILES
The World City Distance Computer system comes in four primary files:
NAME SIZE DESCRIPTION
WCD.EXE 74496 Executable program module
WCD.DAT 27023 Extra cities information
WCD50.DOC Documentation file (ASCII); (this file)
WCDREAD.ME Short program description with latest changes
Check the file sizes with the above figures as a measure of protection
against viruses.
There are additional datafiles included with the filetype "DAT". For
example, WCDUSA.DAT contains extra cities in the USA, Canada, and
Mexico. All of these files are packaged in a self-extracting archive file
called WCD50ZIP.EXE which creates each file when the archive file is
run. The PKZIP Program comes from PKWARE, Inc., 7545 N. Port Washington
Road, Glendale, WI 53217-3442.
The program file, WCD.EXE, must reside on the current directory or path.
A datafile (WCD.DAT is the default) must reside on the current directory
or path for the data to be accessible.
None of these files is copy-protected and it is suggested that the
archive file be saved in a separate place with your other archive and
backup files. Just run it again for a fresh copy of all the files. To
share this software with others, please copy and transmit the ZIP file
alone so that the original program and files will remain intact inside
it.
STARTING THE PROGRAM
The program runs by issuing the command WCD at the DOS prompt. The user
is then asked for a datafile name, with the default specified as
WCD.DAT. If the [Enter] key is pressed the default file will be loaded
if it exists on the current directory or path. If another file name is
specified, it will be loaded. As explained later, this procedure allows
the user to construct his own set of cities data. Loading the datafiles
from a hard disk speeds up the process considerably.
FUNCTION KEYS
[F1] - SEARCH....for a particular string of characters in city list
[F2] - ERASE.....start selection of this particular city over
[F3] - NEW.......start total selection process over
[F4] - COORDS....enter a latitude and longitude instead of city name
[F5] - LASTCITY..use last city chosen for this city input
[F6] - AIRCRAFT..choose a particular aircraft type or cruise speed
[F9] - QUIT......end program and return to DOS (or use [Esc])
DISTANCE INFORMATION SCREEN
Once all of the inputs are provided, a pop-up screen appears in the
lower left which contains output information. It includes distances
(both great circle distance and equivalent still air distance, which are
explained below) in three sets of units, the estimated flying time, the
direct bearing angle from the first city to the second, and an enroute
high altitude winds estimate. Negative winds are headwinds and positive
values represent tailwinds.
The computation of FLIGHT TIME is quite complex. First, the time for
the great circle flight is determined from empirical information on
flight speed as a function of route distance for jet aircraft. This
time is then corrected for winds based upon a model of world high
altitude winds using the specific route flown. This flight time is
accurate to about 10 minutes or 10% of the elapsed flight time,
whichever is greater. The flight time is from "wheels up" to "wheels
down" and therefore does not include any taxi or gate time. It does not
account for traffic delays, airport area maneuvering, airways that do
not closely follow the great circle route, or enroute stops.
The BEARING is the direction of departure from the origin city along the
great circle path toward the destination city. It is measured from the
origin city by basic compass direction. Thus, the bearing from LA to
New York is 65 degrees clockwise from due north (or about
east-northeast) and the bearing from LA to San Francisco is 320 degress
(or about north-northwest). On longer distances, the initial bearing
might seem deceiving because of the great circle routing. For example,
the initial bearing from Tokyo to Los Angeles is 55 degrees, or east
north-east, even though LA is actually south of Tokyo (33 degrees north
latitude for LA, versus 35 degrees for Tokyo). So the shortest distance
from Tokyo to LA actually starts off headed north even though LA is more
southerly! Try it with a globe and string to check for yourself.
A WORD ABOUT DISTANCE AND TIME
The distances computed are based upon the "GREAT CIRCLE DISTANCE (GCD)"
between the two cities, which can be thought of as the route described
by a string pulled taut between the two cities on a globe. This
represents the shortest physical distance between the two cities. City
locations in WCD are specified as the city's airport location. City
center lats/longs are available from some world almanacs and could be
input by the user if desired using the supplemental database. Remember
that WCD computes the SHORTEST distance between cities (i.e., "as the
crow flies"), so it will only be an estimate of driving distances since
cars cannot follow the shortest route.
These great circle distances between cities are geometrically correct
for a spherical globe. For airplane flight purposes, however,
prevailing head or tail winds make the apparent distance different and
should be taken into account. High altitude winds can be greater than
60 knots and are significant for the flight time calculation. For
example, the great circle distance between Los Angeles and New York is
2467 statute miles. But an airplane traveling between these cities
faces a prevailing headwind of 25 knots when headed westbound (i.e. from
New York to LA) and a prevailing tailwind of 22 knots in the other
direction. Thus the eastbound flight is shorter in time than the
westbound because it is assisted by the wind rather than hindered. The
"EQUIVALENT STILL AIR DISTANCE (ESAD)" accounts for this wind effect.
Flying against the wind, the ESAD is greater than the GCD since the
headwind causes the plane to fly longer to reach its destination. Thus
the ESAD from NYC to LA is 2611 statute miles and takes 5 hours and 33
minutes (against the wind) while the ESAD from LA to NYC is 2351 statue
miles and takes only 5 hours and 2 minutes (with the wind's help). This
ESAD is used to compute the flight time that accounts for the effects of
enroute winds. So, although the great circle distance between two
cities is the same in both directions, because of prevailing winds, the
equivalent still air distances and the flight times are not.
IF THIS CONFUSES YOU A LITTLE, just remember that the ACTUAL DISTANCE
between a city pair is the great circle distance (GCD), and that the
FLIGHT TIME is computed to include the effects of the wind in the
correct direction.
AIRCRAFT SELECTOR
Function Key 6 from the Main Menu will allow selection of cruise speeds
for various aircraft types. Commercial jetliners are the default value.
The program also allows the input of a cruise speed value.
Commercial Jetliner 434 Knots
Sabreliner (BizJet) 440 Knots
Kingair (Turboprop) 230 Knots
The program automatically accounts for the fact that aircraft cannot fly
at cruise speed throughout the flight by applying factors from actual
commercial aircraft flying experience.
LOCATION FEATURE
This feature is designed for onboard laptop users in window seats! The
rest of you will have to use your imagination. Once the origin and
destination cities have been selected, the LOCATION option allows you to
determine your enroute position along the great circle route. The
elapsed time since takeoff is entered in hours/minutes (HH.MM), for
example, 8.57 is 8 Hours 57 Minutes, and 0.45 is 45 Minutes enroute
time. Then the user has the option of entering a more accurate total
flight time based upon information from the cockpit. If no more
accurate flight time is available, just press [Enter] and the total
flight time computed by the program in the box on the lower left will be
used. The program then determines your location along the great circle
path and provides a listing of nearby cities with distances from the
aircraft and directions. Since airliners often do not follow the exact
great circle route, but use airways, this location will be an
approximation and the indicated cities will probably not be in exactly
these directions or distances. But they should be in the vicinity, so
keep your eyes open for them. On slower computers, this extensive
search routine can take a minute or more so please be patient. On
faster machines, cities can be determined in 2 to 10 seconds. This is
the closest a passenger will get (for a while) to an inertial navigation
system at their seat!
DATAFILES
The program allows the user to include additional city pairs from
supplementary datafiles. The default datafile is called WCD.DAT. This
file is provided with the programs and contains many additional smaller
or less popular cities that the user may wish to select to be included
in the program when it is run. If you are satisfied with the cities in
the program itself and do not require additional cities, you may remove
this file (WCD.DAT) from the current directory to speed the loading of
the program.
Memory space precludes fitting all of the additional cities within the
program itself. As supplied, only a few additional cities are selected
for loading although hundreds of additional cities will fit. You can
edit this file with a typical line editor (such as KEDIT or EDLIN) to
select other cities or remove those selected by changing Field A as
instructed below. The user can also add additional lines to this file
to include other cities (or locations) of his choosing. The format of
the file, sampled from the middle of the datafile, is as follows:
COLUMN 1 2 3 4 5 6 7
12345678901234567890123456789012345678901234567890123456789012345678901
FIELD....................................................
A B C D E F
...
0, BARRANQUILLA, COLUMBIA, BAQ, 10.54, 74.47
1, BASEL, SWITZERLAND, BSL, 47.35, -7.32
0, BASRA, IRAQ, BSR, 30.33, -47.47
0, BATTLE CREEK, MICHIGAN, BTL, 42.19, 85.15
0, BATTLE MOUNTAIN, NEVADA USA, BAM, 40.36, 116.52
...
0, ZZ***, ******, ***, 0.00, 0.00 (Last Line)
The data columns are not critical, although retaining the existing
columns will make spotting errors easier. The commas between fields ARE
critical since they actually delimit (or separate) the data fields.
Field descriptions:
Field A- 1-INCLUDE in program; 0-Do NOT include.
Field B- Description of City Name (16 characters maximum)
Field C- Additional description such as State & Country (16 char max)
Field D- A Three-Digit City Code designator (Numbers can be used)
Field E- The City Latitude (North of Equator is positive)
Field F- The City Longitude (West of Greenwich is positive)
In the sample data above, Basel would be added to the program
while the other cities would not. The latitudes and longitudes are
given in degrees and minutes in this format: DDD.MM. Be careful with
the proper sign to differentiate north from south and east from west.
If the city name and code of any two cities exactly match, the program
will use the last entry. This prevents duplicate entries and also
allows the user to supply his own data for cities already in the program
itself.
Entire lines of data can be added to or deleted from this file. Thus
you can add new cities such as your hometown. Lines deleted from this
file will make the loading process a little faster, so if you are sure
you don't care about a given city in this file you can eliminate it.
The last line of the file containing dummy fields MUST be preserved
since it indicates the end of the data to the program.
You can always reconstruct the original datafiles from the ZIP file by
re-extracting, but be careful to backup any new datafiles you have
created so they are not overwritten during extraction.
An additional city datafile called WCDUSA.DAT is provided which is
simply a subset of the WCD.DAT file. WCDUSA.DAT contains all cities
from WCD.DAT that are in the United States, Canada or Mexico. For
convenience, all the cities in this file are turned on (with a "1" in
Field A.) This datafile or any other datafile the user specifies will be
loaded into the program if specified when the program is started. Just
remember that it must conform to the formats indicated above.
A FINAL WORD
We hope that you enjoy WCD and will register if you find it valuable and
are using it. That way you will be informed of future enhancements and
will be supporting the shareware concept which allows you to see and try
programs before you pay for them. Where else can you write to the
programmer and offer your ideas for future versions? We've incorporated
many user conceived ideas.
Your comments and suggestions for improvements are always welcomed.
- O - O - O - O - O -