[sdiy] 8080-based synth reliability

[Dave Brown]

It is wire wrapped, on a PCB about 4"x6" or so.  The +12 and +5 are derived
from linear regulators from the doorbell transformer and the -5 is derived
from a switcher.  The 8080 I put in it was in foam for 40+ years which
deteriorated so the leads are a bit pitted.  I think I have another 8080
somewhere so if I switch it out I will take photos and put a page on my
site.  I built my own 8080 computer and wire wrapped a number of the boards.
We thought nothing of wire wrapping for hours on end, day after day, for
these projects.

Dave

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
> MTG
> Sent: Friday, October 06, 2017 1:41 PM
> To: synth-diy at synth-diy.org
> Subject: Re: [sdiy] 8080-based synth reliability
> 
> If nothing else I'd love to see photos.  I'm guessing some wire-wrapped
> beast. Awesome!  I still have a 6809 breadboard system from the old days.
> It's not doing anything though. :-(
> 
> On 10/6/2017 12:54 PM, Dave Brown wrote:
> > 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.
> >
> > 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.
> >
> > 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.
> >
> >
> > Dave
> >
> > David J. Brown
> >
> > Modular Synthesis, LLC
> >
> > http://modularsynthesis.com <http://modularsynthesis.com/>
> >
> >
> >
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