[BBF Standards] systemic limitation of biobricks for combinatorial logic?

[Herbert Sauro]

Funny you should mention this solution:

 > Can this be solved by using single cells for each circuit, then
 > somehow providing inter-cell communication?
 > (Also seems quite difficult, correct?)

Because this is how evolution got round the problem by inventing neural 
circuits.

Herbert Sauro

J C wrote:
> Hi all,
> I have been reading about biobricks for some time,
> I am a computer engineer.
> 
> For combinatorial logic, it seems the limitation of biobricks
> is the system-wide visibility of all gate outputs, is this correct?
> In circuits with multiple gates, each gate must employ a unique
>  input signal and output signal, otherwise the multiple outputs
> will conflict with the inputs.
> 
> How is this being addressed other than by finding unique
> signals to feed to each gate?
> 
> This is not a scalable solution for larger circuits, i.e. adders
> or latches (RAM storage for more than 1 bit).
> 
> Can this be solved by using single cells for each circuit, then
> somehow providing inter-cell communication?
> (Also seems quite difficult, correct?)
> 
> There was a similar comment on this recently, though I didn't
> see any solution discussion?
> http://biobricks.org/pipermail/standards_biobricks.org/2008-February/000034.html
> "The lack of physical separation of signals, as is the case in
> microelectronics, could be one of the biggest limitations to the
> standardized bioparts concept. "
> 
> 
> The idea offered in that thread,
> "Actually this could lead to a design process where you operate e.g. on a
> system level and design your nice circuit, but depending on the circuit the
> design computer programme chooses one of different devices (and finally
> parts) that interact in the way you like."
> 
> This is actually quite impossible for multi-gate designs.  A multi-bit adder
> or memory storage would require far too much complexity.  The components
> (i.e. "transistors") need to have completely compatible outputs so that
> any output can connect to any input.  Otherwise they are not "generic parts".
> Similar issues led to much complexity in the early days of semiconductor
> fab.
> 
> --
> Cheers!
> 
> _______________________________________________
> Standards mailing list
> Standards at biobricks.org
> http://biobricks.org/mailman/listinfo/standards_biobricks.org