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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I’d have to look for the source. Note it was written in assembler and has to execute out of RAM since it entails self-modifying code. Those two facts may rule out anyone younger than 50. I’ll see if I can dig up the code. I might have it somewhere.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><br>Dave<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Ove Ridé [mailto:nitro2k01@gmail.com] <br><b>Sent:</b> Friday, October 06, 2017 1:08 PM<br><b>To:</b> Dave Brown<br><b>Cc:</b> Synth DIY<br><b>Subject:</b> Re: [sdiy] 8080-based synth reliability<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>You ought to document the project for posterity and 5 minutes of Hackaday fame. If you post a ROM dump or perhaps source code if it survived for all these years, the project might take on a modern life on its own by dedicated hackers. (I for one wouldn't mind looking at it.)<br><br>On Friday, 6 October 2017, Dave Brown <<a href="mailto:davebr@modularsynthesis.com">davebr@modularsynthesis.com</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>This is definitely DIY related and somewhat synth related in that it is a digital 3 voice synthesizer. In late 1976 I designed a dedicated 8080 based three voice PWM synthesizer as a doorbell. The code was based on a program called Music for the Processor Technology Sol-20 computer. I had to disassemble the program to get it to run on a basic 8080 system using a single 2708 EPROM and two 2114 static rams. It used a simple transistor driver for the speaker. The 8080 is unmarked so I think it might even be an engineering sample.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>This system has continuously run for approximately 14,870 days or nearly 356,880 hours. Well this week it died. The processor is just absolutely lifeless. I had another 8080 from the same vintage but at least marked and replacing it brought the system back to life. Note that in the 40 years the 2708 has not forgotten even though the guaranteed retention is only 10 years. I think it will outlive me.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>It was a really progressive program for the time. This doorbell also includes a RS-232 interface so I could compile new music to upload to it for special occasions.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><br>Dave<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>David J. Brown</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Modular Synthesis, LLC</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><a href="http://modularsynthesis.com/" target="_blank"><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>http://modularsynthesis.com</span></a><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><br><br>-- <br>/Ove<br><br>Blog: <<a href="http://blog.gg8.se/" target="_blank">http://blog.gg8.se/</a>><br><br>"Here is Evergreen City. Evergreen is the color of green forever."<o:p></o:p></p></div></div></body></html>