[no subject]

Knowing all of this, we can design interface circuits. Such 
devices as photocells, photo resistors, thermisters, and other 
things could be connected to the game port. With appropriate 
software, we could use the Apple to monitor a variety of 
real-world events, and to display the results.

For example, a local chemistry lab wanted to measure the "time 
of solution" when a chemical was dropped into a test tube 
containing a solvent. The solvent was clear, but changed color 
when the chemical dissolved into it. A light was passed through 
the test tube to strike a photo resistor. A TYPE 7 photo resistor, 
which has peak sensitivity with orange light, varies its 
resistance as a function of light intensity, with the formula

R = (443)*(I^(-0.6692))

where R is in Kilohms and I is in foot-candles. Futhermore, the 
minimum sensitivity of the photo resistor is with violet light, 
which happens to be the color when thiothymolyne is dissolved 
in water.

When the photo resistor is connected to the paddle input with 
33 volt source, the resistance in Megohm is calculated by the 
approximation;

R = (count)/209.9

The point of all this was an attempt to refute the results 
obtained by Prof. Azimov, as reported in April 1948. The Prof. 
had reported that thiothymolyne displays a negative "time of 
solution" when dropped into water. Prof. Azimov may have been 
correct. Unfortunately, meaningful results could not be obtained 
from the above experiment because the Apple II is too slow to 
measure negative time. Perhaps one of the new optical computers, 
which operates at the speed of light, could be fitted with an 
accelerator to operate faster than light, and thus be used to 
measure negative time.

Of course, some of this is in jest. But such interfaces are 
practical, within the limitations of the Apple II game port.


Cyrus Roton   croton@ridgecrest.ca.us
Ridgecrest Apple User Group