by Bruce Horn
[image]A Smalltalk Airplane Simulation *** by Bruce Horn *** My name is Bruce Horn, and I am a junior at Gunn Senior High School in Palo Alto, California. I have been programming for about 3 years, mostly in Basic or Algol on Hewlett-Packard systems, such as the HP-3000. I would usually write simulations of other languages in Basic, or some type of mathematical program such as a program to plot equations. At the end of the first semester, one of the math teachers asked me if I would like to get some Exploratory Experience credit (a program for work experience without pay) for working with computers at Xerox. I remember visiting the Xerox Palo Alto Research Center (PARC) one time before, so I decided that it would be a great experience. Since then, I have been working on one major project: an airplane simulator. The computer that we use at PARC is a single user computer with a disc drive, keyboard, a graphics display, a five finger keyset and a pointer called a mouse. Since it is not timeshared, the machine responds quickly. It uses a totally new language called Smalltalk. My idea of an airplane simulation is a program that would totally imitate the movements and attitude of an actual airplane, including the instruments used and the actual positions of the horizon that you see. An ideal simulation on a computer would have to be realistic enough to be interesting. This would involve realistic output so that you could really see what is going on, and convenient input (stick, throttle, rudder) so that you can control the simulated airplane easily. The basic idea behind Smalltalk is the concept of classes and instances. Programming in Smalltalk means that you *** [image] 1. Photograph of the display screen showing the airplane flying straight and level (with no bank). *** [image] 2. Airplane is in a turn - banking and depressing the right rudder pedal. *** 37
