114 lines
5.9 KiB
Text
114 lines
5.9 KiB
Text
PLAYING MOONLANDER (LEM)
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The object of moonlander is to land a lunar module on the
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surface of the moon. The program will run on any 8K GT40
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with a light pen and a clock. If you are attached to a PDP-10
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you may use the ROM bootstrap to bring over the assembled
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binary. If you are not "talking" to a PDP-10, you may load
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in the binary loader (absolute loader) and load in the paper
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tape version of the program. Note: the program will destroy
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the binary loader when it starts running.
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When the program is loaded, it will automatically start and
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display an "introductory message" on the screen. Future
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restart of the program will not cause this message to be
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displayed. Should any problems occur, the program may be
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restarted at any time at location zero (000000). Power fail
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protection is also provided. After starting (or restarting),
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you then start playing the actual game. All numbers, speeds,
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weights, etc., are actual numbers. They are for real. To
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make the game more possible for an average person to play, I
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have given him about 25 to 50% more fuel in the final stages
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of landing than he would actually have.
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What the user sees on the screen is a broad and extremely
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mountainous view of the moon. On the right is a list of data
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parameters which the user may examine. They are height,
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altitude, angle, fuel left, thrust, weight, horizontal velocity,
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vertical velocity, horizontal acceleration, vertical accelera-
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tion, distance and seconds. At the top of the screen, any
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four of the values may be displayed. To display an item, the
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user points the light pen at the item he wishes to display.
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The item will then start blinking, to indicate that this is the
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item to be displayed. The user then points the light pen at
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one of the previously displayed items at the top of the screen.
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The old item disappears and is replaced by the new item.
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Note that it is possible to display any item anywhere, and even
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possible to display one item four times at the top. Anyway,
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the parameters mean the following. Height is the height in
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feet above the surface (terrain) of the moon. It is the "radar"
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height. Altitude is the height above the "mean" height of the
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moon ( I guess you would call it "mare" level). Thus altitude
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is not affected by terrain. Angle is the angle of the ship in
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relationship to the vertical. 10 degrees, -70 degrees, etc.
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Fuel left is the amount of fuel left in pounds. Thrust is the
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amount of thrust (pounds) currently being produced by the engine.
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Weight is the current earth weight of the ship. As fuel is
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burned off, the acceleration will increase due to a lessening of
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weight. The horizontal velocity is the current horizontal speed
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of the ship, in feet per second. It is necessary to land at
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under 10 fps horizontal, or else the ship will tip over.
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Vertical velocity is the downward speed of the ship. Try to
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keep it under 30 for the first few landings, until you get
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better. A perfect landing is under 8 fps. The horizontal
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and vertical accelerations are just those, in f/sec/sec.
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With no power, the vertical acceleration is about 5 fp/s/s
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down (-5). Distance is the horizontal distance (X direction)
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you are from the projected landing site. Try to stay within
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500 feet of this distance, because there are not too many
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spots suitable for landing on the moon. Seconds is just the
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time since you started trying to land. Thus you now know how
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to display information and what they mean.
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To control the ship, two controls are provided. The first
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controls the rolling or turning of the ship. This is accom-
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plished by four arrows just above the display menu. Two point
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left and two point right. The two pointing left mean rotate
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left and the two pointing right mean rotate right. There is
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a big and a little one in each direction. The big one means
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to rotate "fast" and the small one means to rotate "slow".
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Thus to rotate fast left, you point the light pen at
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left arrow. To rotate slow right, you point the light pen at
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the small arrow pointing to the right. The arrow will get
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slightly brighter to indicate you have chosen it. Above the
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arrow there is a bright, solid bar. This bar is your throttle
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bar. To its left there is a number in percent (say 50%). This
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number indicates the percentage of full thrust your rocket
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engine is developing. The engine can develop anywhere from
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10% to 100% thrust - full thrust is 10,500 pounds. The
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engine thrust cannot fall below 10%. That is the way Grumman
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built it (actually the subcontractor). To increase or decrease
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your thrust, you merely slide the light pen up and down the bar.
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The indicated percentage thrust will change accordingly.
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Now we come to actually flying the beast. The module appears
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in the upper left hand corner of the screen and is traveling
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down and to the right. Your job is to land at the correct
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spot (for the time being, we will say this is when the
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distance and height both reach zero). The first picture you
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see, with the module in the upper left hand corner, is not
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drawn to scale (the module appears too big in relationship
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to the mountains). Should you successfully get below around
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400 feet altitude, the view will now change to a closeup
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view of the landing site, and everything will be in scale.
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Remember, it is not easy to land the first few times, but
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don't be disappointed, you'll do it. Be careful, the game
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is extremely addictive. It is also quite dynamic.
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Incorporated in the game are just about everything the GT40
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can do. Letters, italics, light pen letters, a light bar,
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dynamic motion, various line types and intensities (the moon
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is not all the same brightness you know). It also shows that
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the GT40 can do a lot of calculations while maintaining a
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reasonable display.
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There are three possible landing sites on the Moon:
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1. On the extreme left of the landscape
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2. A small flat area to the right of the mountains
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3. In the large "flat" area on the right
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Good Luck!
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