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dTalk -Build the Circuit




It was July of 1983 when Antic published the software/hardware project “Talk is Cheap” by Ed Stewart. The hardware hooked up a microphone to a paddle port and the software collected and stored the sound data for playback. The hardware is not overly complicated and would be fun to build even if you are going to use it with the original software. I want to see how far I get trying to use the Diamond GOS for setting and selecting the options..


The original article along with the program can be obtained at www.atarimagazines.com. When it first appeared in July 1983 the program listings were not included. The August issue had the program listings in the HELP section. Then in October it was pointed out that the schematic was labeled wrong. It should read PortA(pin 9) and not Ground(pin9). The article provides a good explanation of how the software works and ideas on how to build the circuit.


My build:




The circuit consists of 5 components. My local parts store had the capacitor and the rest were in my salvaged parts cabinet. I splurged on a new microphone, Originally I was going to cut the cord but later decided to use the plug (I still might cut the cord). A search of Amazon for “moving coil microphone” displayed some relatively inexpensive microphones. I picked the $3.99 model then spent another $50 for the free shipping.


An Altoids tin is big enough to hold the project. A 9-Pin socket was mounted on the end and a game port extension cable will connect the circuit to the computer. (an old joystick cable will not work because it has no wires connected to the paddle port pins). The variable resister holds the circuit in place, The duct tape on the inside of the lid should keep it from shorting out if it becomes loose.






Knowing it was going to be photographed required that time and effort be spent putting it in the box. Imagine what the projects that don't get photographed look like


Testing the circuit.


Plug the circuit into the joystick port and boot up with BASIC. You can run the original program to evaluate your handy work or.....


Run this program.


10 ? PADDLE(0)

20 FOR X = 1 TO 100:NEXT X

30 GOTO 10


The paddle value will print to the screen. Adjust the variable resistor and the number should change. Screaming into the microphone should change the value. Mine does. Make sure your reading the paddle value for the one you are plugged into.


What's Next


A quick look at the BASIC code for “Talk is Cheap” makes be believe there's a problem. Seems the USR routine to digitize the port input and the link code to Diamond may have problems working together. Both are loaded into the same Page 6 location. I'm thinking, “That's not a good thing.”



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