🚀 go-pugleaf

In article <11566@sun13.scri.fsu.edu> rms@well.sf.ca.us (richard
marlon stein) writes:
...
>Try muxing the outputs from 1000 framebuffers into a single analog stream.
>I would rather pass on this approach.  The PixelFlow box captures the output 
>from a composition network rated at 4 Gbytes/s into a single frambeubffer.
>
>I don't believe this approach is truly scalable either, since its still
>an example of the N to 1 mux problem.  So it is, in my opinion, contention
>limited (the laws of physics won't cooperate and provide infinite digital
>bus or network bandwidth).

Since I work on PixelFlow, I feel compelled to comment on this.  The
PixelFlow composition network is scalable precisely because it doesn't
suffer from contention problems.  Each node composites its output with
the composited output of the nodes before it and sends it on to the
nodes after it.  It's a straight chain of boards so there is no
contention; each board dealing only with two sources for a single
pixel that it has to choose between for its single pixel output.  The
network is pixel-pipelined so adding an extra board just adds another
pixel-time's worth of latency to the composition.  The scalability
limits are not with numbers of nodes, but with display size since the
composition network speed is determined by the number of pixels you
want to push through per second.

-marc (olano@cs.unc.edu)
Grad student, University of North Carolina at Chapel Hill

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