84A-19 POPULAR MECHANICS

OCT 1979

Computer goes for the gold

When our Olympic athletes stride pridefully to the awards platform, many of them may be silently thanking a cybernetic partner-an Eclipse S!250 computer and peripherals. Donated by Data General (screen from Megatex Corp), the computer will help our Olympic hopefuls to help themselves.

When an athlete competes or trains, not even a careful coach's eye can catch every nuance of movement in order to suggest helpful changes. The computer can.

A high-speed film is used (up to 10,000 frames per second) to capture the athlete's efforts. Then comes the computer. It breaks the film down frame by frame and examines the forces generated by the joints in the competitor's shoulder, upper arm, forearm, wrist, hands and knees. The computer then displays stickfigure images of the athlete on the display screen.

Touch a pen to any of the pictured joints and the c',:nputer will calculate the velocity, acceleration, direction and angle of the forces generated by that body segment. Now curries the con,l.uter

According to Dr. Gideon Ariel, a member of the Sports Medicine Committee and one of the computer's programmers, "That way we know beforehand whether a change would help or not. This makes it much easier fur a coach to suggest something new to the athlete since he already knows it will work."

The visible calculator

I was recently allowed to preview a software program that-in my opinion--will revolutionize personal computing. With VisiCalc and a home computer, everyone-not just professionals-will be able to custom-design his own specialized computer programs.

VisiCalc puts on the screen any section .f a grin of about 3llii ht-: itti blocks. Any block, and its relationship to any other block, can be instantly entered by plain English and mathematical formulas. If you want block B) to be labeled "Profit," you can define it in terms of cost and selling price, or whatever you would like.

If you change a variable, say percent of interest in a savings account,

Getting the speakers out-of-phase is ore of the most common errors made when hooking up a stereo system. Luckily, it is also the easiest to remedy.

Two speakers that are in-phase will move their speaker cones identically, given the same input signal. Out-of-phase means fiat when one speaker's cone is moving out the other's is moving in-and vice versa. The wins, or at least lessens, good stereo.

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seem to come from oetween the speaketkif you are centered between them and t!e balance is eaual. f not, check your phasng.

every figure dependent on that Tariable instantly changes. Think o' all the "what-ifs" you can check out quickly: What a rent increase via do to your family budget: what varying Dow Jones averages could do to your stock portfolio; how changer in wholesale prices will affect your business statement. Possibilities are endless.

We'll examine Vi;iCalc in n:..rr detail in a later article. Suffice it to say that it will soon be available fox just

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Programming for personal or busirws financial management is easy with VisrCalc.

about every home computer and you can write to Personal Software, box 136-M, Cambridge, Mass. 0�138, for more information.

End tape hassles

'host home computers will allow you to save a program on audio tape and then reprogram the computer by simply playing the tape into do input (page 66, Aug. 79). But many computers are quite sensitive to stray noises or interruptions on the tape and it may take several tries before the program is accepted.

The Data Enhancer from Microsette (777 Palomar Ave., Sunnyvale, Calif. 94086) plugs between the recorder and a Radio Shack TRS-80 computer. By sensing the first pulse and "knowing" when the next pulse should come it allows the computer to ignore spurious noise or hum.

It's worthwhile at $45 and we hope similar units become available for the other home computers. RI

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Make your stereo sound right!

Many speaker terminals are marked either plus (}) or minus(-) or are color-coded Be certain that wires from the speaker terminals go to the same relatively positioned or marked output terminals on your amplifier (as pictured). This will insure in-phase operation, (If you use RCA-style plugs, make sure the shields and inside wires maintain the same relative relationship

Use special speaker wire having some

identification code. such as c^e lead or cop

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make out-of-phase hookups east to av0,d. Don't let a simple wiring error ruin your costly stereo vestment.

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