These are some improvements on the bio programs which operate with the Hal 
interface from Circuit Cellar.  I found that original programs were not much
use when trying to monitor and train myself to produce alpha waves.  This 
program graphs 5 frequency bands over an adjustable period of time. 
It is an improved version of bio2 by Christopher Scavetto.
I checked the design of the interface and tested frequency response and found
that the low frequencies were rolled off pretty drastically. Particularly
a 6 db rolloff at 9 hz  due the action of C1 and C2. I therefore increased
C2 and C2 to 10 uf from 3.3 uf and got much better results. I hope you enjoy
and find these programs of value.  Greg Birdsall
                                   1972 Whyte Ave.
                                   Vancouver, B.C.
                                   Canada V6J 1B3 
Bio4.exe and biocga.exe are stand alone ready to run programs.
Be sure to select appropriate com port with F1.
The makebio4.bat file will recompile bio4.bas from quick basic 4.5 if you 
would like to make any more changes.  I am running this program on a 486-66 
computer. It can bog down on a slower machine.  
The biocga program is designed for a 286 laptop or similar machine with CGA
screen.
I didn't like sticking the electrodes on my head so I designed an elastic 
headband, adjustable with velcro, behind which I tuck the electrodes. I use a
clip on ear ring with an electrode attached for the ground. This clips on the 
ear lobe. The electrodes are moistened with a saline gell used for electro-
cardiography. I used the silver/silver chloride electrodes which come with 
Hal but taped over the sticky part.
I also found that rg-59 rf cable was less noisy than audio cable for the 
electrode wires.
