SV: TB-303 original power supply - Answerfrom author

[Jeroen Proveniers]

> -----Original Message-----
> From: Trevor Page [mailto:trevor at resonance.fsnet.co.uk]
> Sent: Friday, August 04, 2000 9:52 PM
> To: *Star Project; DIY skicka Lista
> Subject: Re: SV: TB-303 original power supply - Answerfrom author
> 
> 
> Hi Andreas and all,
> 
> Regarding the sequencer - just a reminder that the TB303's custom
> microcontroller is no longer available, not even from Roland 
> and therefore
> it will not be possible to clone the sequencer exactly. New 
> firmware will
> have to be written for a modern device, eg PIC / Atmel. Since 
> you mention
> the memory circuit, I presume you are intending to clone the 
> sequencer.
> 
> > However the battery supply still has to included
> > so that it works the same way since the memory
> > depends on the battery supply.
> 
> This will not be necessary, since a modern sequencer clone is 
> unlikely to
> use volatile static-RAMs. Rather, modern EEPROM devices will 
> be used which
> do not require the use of a backup supply. Your power supply 
> circuit would
> not need to provide a backup supply line from the battery.

Somewhere in the future I'm planning to clone the sequencer, it cannot
really be difficult to do.
E2PROMs have a limited number of writecycles, 100.000 cycles guaranteed for
most devices. The firmware needs to take account of that, probably just
writing the E2PROM on power down. The hardware must include some big
capacitor to keep the processor running for a while after power down. I
would still prefer some static RAM. E2 is more interesting for information
that does not change that often, configuration or calibration data for
example.

JJ
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