ATC(6)

NAME
atc - air traffic controller game

SYNOPSIS
atc [-lpqst] [-f game] [-g game] [-r seed]

DESCRIPTION
atc lets you try your hand at the nerve-wracking duties of an air traffic controller without endangering the lives of millions of travelers each year. Your responsibilities require you to direct the flight of jets and prop planes into and out of the flight arena and airports. The speed (update time) and frequency of the planes depend on the difficulty of the chosen arena.

-f game
    Play the named game. If the game listed is not one of the ones printed by the -l option, the default game is played.

-g game
    Same as -f.

-l  Print a list of available games and exit. The first game name printed is the default game.

-p  Print the path to the special directory where atc expects to find its private files. This is used during the installation of the program.

-q  Play quietly (no bells).

-r seed
    Set the random seed. This option can be used to replay a specific game.

-s  Print the score list (formerly the Top Ten list). The scoring information is the game time in “radar updates”, the wall-clock game time, and the number of planes that were successfully dealt with.

-t  Same as -s.

GOALS
Your goal in atc is to keep the game going as long as possible. There is no winning state, except to beat the times of other players. You will need to: launch planes at airports ( by instructing them to increase their altitude); land planes at airports (by instructing them to go to altitude zero when exactly over the airport); and maneuver planes out of exit points.

Several things will cause the end of the game. Each plane has a destination (see information area), and sending a plane to the wrong destination is an error. Planes can run out of fuel, or can collide. Collision is defined as adjacency, horizontal or vertical. A plane leaving the arena in any other way than through its correct destination exit is an error as well.

Scores are sorted in order of the number of planes safe. The other statistics are provided merely for fun. There is no penalty for taking longer than another player (except in the case of ties).

Suspending a game is not permitted. If you get a talk message, tough. When was the last time an Air Traffic Controller got called away to the phone?

THE DISPLAY
Depending on the terminal used, the atc screen will be divided into 4 areas. It should be stressed that the terminal driver portion of the game was designed to be reconfigurable, so the display format can vary depending on the version you are playing. The descriptions here are based on the ASCII version of the game. The game rules and input format, however, should remain consistent. Control-L redraws the screen, should it become muddled.

  RADAR
The first screen area is the radar display, showing the relative locations of the planes, airports, standard entry/exit points, radar beacons, and “lines” which simply serve to aid you in guiding the planes.

Planes are shown as a single letter with an altitude. If the numerical altitude is a single digit, then it represents thousands of feet. Some distinction is made between the prop planes and the jets. On ASCII terminals, prop planes are represented by an upper case letter, jets by a lower case letter.

Airports are shown as a number and some indication of the direction planes must be going to land at the airport. On ASCII terminals, this is one of ‘^’, ‘>’, ‘<’, or ‘v’, to indicate north (0 degrees), east (90), west (270), and south (180), respectively. The planes will also take off in this direction.

Beacons are represented as circles or asterisks and a number. Their purpose is to offer a place of easy reference to the plane pilots. See The Delay Command under the input section of this manual.

Entry/exit points are displayed as numbers along the border of the radar screen. Planes will enter the arena from these points without warning. These points have a direction associated with them, and planes will always enter the arena from this direction. On the ASCII version of atc, this direction is not displayed. It will become apparent what this direction is as the game progresses.

Incoming planes will always enter at the same altitude: 7000 feet. For a plane to depart successfully through an entry/exit point, it must be flying at 9000 feet. It is not necessary for the planes to be flying in any particular direction when they leave the arena (yet).

  INFORMATION AREA
The second area of the display is the information area, which lists the time (number of updates since start) and the number of planes you have directed safely out of the arena. Below this is a list of planes currently in the air, followed by a blank line, and then a list of planes on the ground (at airports). Each line lists the plane name and its current altitude, an optional asterisk indicating low fuel, the plane's destination, and the plane's current command. Changing altitude is not considered to be a command and is therefore not displayed. The following are some possible information lines:

    B4*A0: Circle @ b1

    g7 E4: 225

The first example shows a prop plane named ‘B’ that is flying at 4000 feet. It is low on fuel (note the ‘*’). Its destination is Airport #0. The next command it expects to do is circle when it reaches Beacon #1. The second example shows a jet named ‘g’ at 7000 feet, destined for Exit #4. It is just now executing a turn to 225 degrees (Southwest).

  INPUT AREA
The third area of the display is the input area. It is here that your input is reflected. See the INPUT heading of this manual for more details.

  AUTHOR AREA
This area is used simply to give credit where credit is due. :-)

INPUT
A command completion interface is built into the game. At any time, typing ‘’? will list possible input characters. Typing a backspace (your erase character) backs up, erasing the last part of the command. When a command is complete, a return enters it, and any semantic checking is done at that time. If no errors are detected, the command is sent to the appropriate plane. If an error is discovered during the check, the offending statement will be underscored and a (somewhat) descriptive message will be printed under it.

The command syntax is broken into two parts: Immediate Only and Delayable commands. Immediate Only commands happen on the next update. Delayable commands also happen on the next update unless they are followed by an optional predicate called the Delay command.

In the following tables, the syntax [0-9] means any single digit, and <dir> refers to the keys around the ‘s’ key, namely “wedcxzaq”. In absolute references, ‘q’ refers to Northwest or 315 degrees, and ‘w’ refers to North, or 0 degrees. In relative references, ‘q’ refers to -45 degrees or 45 degrees left, and ‘w’ refers to 0 degrees, or no change in direction.

All commands start with a plane letter. This indicates the recipient of the command. Case is ignored.

  IMMEDIATE ONLY COMMANDS

a [ cd+- ] number
    Altitude: Affect a plane's altitude, possibly requesting takeoff. ‘+’ and ‘-’ are the same as ‘c’ and ‘d’.
    a [0-9]
        Go to the given altitude (thousands of feet).
    c [0-9]
        Climb: Relative altitude change (thousands of feet).
    d [0-9]
        Descend: Relative altitude change (thousands of feet).

m   Mark: Display in highlighted mode. Plane and command information is displayed normally.

i   Ignore: Do not display highlighted. Command information is displayed as a line of dashes if there is no command.

u   Unmark: Same as ignore, but if a delayed command is processed, the plane will become marked. This is useful if you want to forget about a plane during part, but not all, of its journey.

  DELAYABLE COMMANDS

c   Circle: Have the plane circle.

t [ l-r+LR ] [ dir ] or tt [ abe* ] number
    Turn: Change direction.
    t<dir>
        Turn to the absolute compass heading given. The shortest turn will be taken.
    tl  Left: Turn counterclockwise (45 degrees by default).
        tl <dir>
            Turn ccw the given number of degrees. Zero degrees (‘w’) is no turn; 45 degrees ccw is ‘e’. The shortest turn will be taken; for instance, if you specify a ccw turn of 315 degrees (‘q’), which should take several turns, the plane will really turn 45 cw, which takes only one turn.
    tr  Right: Turn clockwise (45 degrees by default).
        tr <dir>
            Analogous to turn left <dir>.
    tL  Turn counterclockwise 90 degrees.
    tR  Turn clockwise 90 degrees.
    tt [abe*]
        Towards: Turn towards a beacon, airport or exit. The turn is just an estimate.
        ttb number
            Turn towards the specified beacon.
        tt* number
            Equivalent to ttb.
        tte number
            Turn towards the specified exit.
        tta number
            Turn towards the specified airport.

  THE DELAY COMMAND
The Delay (a/@) command may be appended to any Delayable command. It allows the controller to instruct a plane to do an action when the plane reaches a particular beacon (or other objects in future versions).

a/@ At: Do the given delayable command when the plane reaches the given beacon.
    ab number
        The letter is redundant to allow for expansion. ‘@’ can be used instead of ‘a’.

  MARKING, UNMARKING AND IGNORING
Planes are marked by default when they enter the arena. This means they are displayed in highlighted mode on the radar display. A plane may also be either unmarked or ignored. An ignored plane is drawn in unhighlighted mode, and a line of dashes is displayed in the command field of the information area. The plane will remain this way until a mark command has been issued. Any other command will be issued, but the command line will return to a line of dashes when the command is completed.

An unmarked plane is treated the same as an ignored plane, except that it will automatically switch to marked status when a delayed command has been processed. This is useful if you want to forget about a plane for a while, but its flight path has not yet been completely set.

As with all of the commands, marking, unmarking and ignoring will take effect at the beginning of the next update. Do not be surprised if the plane does not immediately switch to unhighlighted mode.

  EXAMPLES

atlab1
    Plane A: turn left at beacon #1

cc  Plane C: circle

gtte4ab2
    Plane G: turn towards exit #4 at beacon #2

ma+2
    Plane M: altitude: climb 2000 feet

stq Plane S: turn to 315

xi  Plane X: ignore

OTHER INFORMATION

•   Jets move every update; prop planes move every other update.

•   All planes turn at most 90 degrees per movement.

•   Planes enter at 7000 feet and leave at 9000 feet.

•   Planes flying at an altitude of 0 crash if they are not over an airport.

•   Planes waiting at airports can only be told to take off (climb in altitude).

•   Pressing return (that is, entering an empty command) will perform the next update immediately. This allows the player to “fast forward” the game clock if nothing interesting is happening.

NEW GAMES
The Game_List file lists the currently available play fields. New field description file names must be placed in this file to be playable. If a player specifies a game not in this file, the score will not be logged.

The game field description files are broken into two parts. The first part is the definition section. Here, the four tunable game parameters must be set. These variables are set with the syntax:

    variable = number;

Variable may be one of: update, indicating the number of seconds between forced updates; newplane, indicating (about) the number of updates between new plane entries; width, indicating the width of the play field; or height, indicating the height of the play field.

The second part of the field description files describes the locations of the exits, the beacons, the airports and the lines. The syntax is as follows:

beacon:
    (x y) ... ;
airport:
    (x y direction) ... ;
exit:
    (x y direction) ... ;
line:
    [ (x1 y1) (x2 y2) ] ... ;

For beacons, a simple x, y coordinate pair is used (enclosed in parentheses). Airports and exits require a third value, a direction, which is one of “wedcxzaq”. For airports, this is the direction that planes must be going to take off and land, and for exits, this is the direction that planes will be going when they enter the arena. This may not seem intuitive, but as there is no restriction on direction of exit, this is appropriate. Lines are slightly different, since they need two coordinate pairs to specify the line endpoints. These endpoints must be enclosed in square brackets.

All statements are semi-colon (;) terminated. Multiple item statements accumulate. Each definition must occur exactly once, before any item statements. Comments begin with a hash (#) symbol and terminate with a newline. The coordinates are between zero and width-1 and height-1 inclusive. All of the exit coordinates must lie on the borders, and all of the beacons and airports must lie inside of the borders. Line endpoints may be anywhere within the field, so long as the lines are horizontal, vertical or exactly diagonal.

  FIELD FILE EXAMPLE

    # This is the default game.
    update = 5;
    newplane = 5;
    width = 30;
    height = 21;
    exit:		( 12  0 x ) ( 29  0 z ) ( 29  7 a ) ( 29 17 a )
    		(  9 20 e ) (  0 13 d ) (  0  7 d ) (  0  0 c ) ;
    beacon:		( 12  7 ) ( 12 17 ) ;
    airport:	( 20 15 w ) ( 20 18 d ) ;
    line:		[ (  1  1 ) (  6  6 ) ]
    		[ ( 12  1 ) ( 12  6 ) ]
    		[ ( 13  7 ) ( 28  7 ) ]
    		[ ( 28  1 ) ( 13 16 ) ]
    		[ (  1 13 ) ( 11 13 ) ]
    		[ ( 12  8 ) ( 12 16 ) ]
    		[ ( 11 18 ) ( 10 19 ) ]
    		[ ( 13 17 ) ( 28 17 ) ]
    		[ (  1  7 ) ( 11  7 ) ] ;

ENVIRONMENT

LOGNAME
    Name to be recorded in high score file.

FILES
Files are kept in a special directory, which can be shown by using the -p flag.

$HOME/.atc.scores
    Score file.
/usr/share/games/atc/Game_List
    The list of playable games.

AUTHORS
-nosplit Ed James, UC Berkeley: edjames@ucbvax.berkeley.edu, ucbvax!edjames

This game is based on someone's description of the overall flavor of a game written for some unknown PC many years ago, maybe.

BUGS
The screen sometimes refreshes after you have quit.