Building a Sound Board For C1P

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Jeff
Posts: 245
Joined: Fri Mar 07, 2014 4:44 am
Location: British Columbia, Canada

Building a Sound Board For C1P

Post by Jeff » Fri May 15, 2015 9:52 pm

I found this article languishing in my old Challenger documentation. Perhaps some people here might find it interesting.

http://www.jeffferguson.ca/OSI/Hardware ... %20C1P.PDF

Enjoy!
/Jeff
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Jeff
Posts: 245
Joined: Fri Mar 07, 2014 4:44 am
Location: British Columbia, Canada

Re: Building a Sound Board For C1P

Post by Jeff » Wed Nov 08, 2017 5:49 pm

Link Restored
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Scott Larson
Posts: 18
Joined: Fri Nov 14, 2008 8:32 pm

Re: Building a Sound Board For C1P

Post by Scott Larson » Mon Feb 18, 2019 5:58 pm

The SN76477 is an analog chip and the best you could do was trigger it. You really had no programmatic control over the sounds.

What I did for fun was make a very very crude digital to analog converter. I used a 74273 as an 8 bit latch (I had already done this for a parallel printer port) and put the eight outputs through a resistor network (1K, 2K, 4K, etc.) and connected that to an amplifier. The sounds I got were very crude and distorted since I had no clue I needed a low pass filter, but I was impressed at what a little circuit could do. I was able to do some pulse width modulation and sending random values made explosions and white noise.

I was tempted to make something like an 8 bit sampler, something with like 2K of RAM to hold the waveform and with the 8 bit value setting the frequency. The cycling part of the circuit was easy because it was much like the video of the C1P, but I could not figure out how to control the speed of the circuit with an 8 bit value.

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