BE/LE

["Philip Ronzone" <Philip.Ronzone@eng.efi.com>]

  > >   > A simple form of what Andy Grove called Native Signal
  > >   > Processing that comes into use on a few unexpected points
  > >   > in our last designs. In a small new design it gives us an
  > >   > unexpected 10% price reduction on hardware. For $2.50 we
  > >   > buy a CPU that's twice as fast and only need stupid driver
  > >   > IC's instead of the $10 for two costly highly integrated
  > >   > circuits that others use...
  > > 
  > > By extending that logic, we can drop all UARTs as well, right?
  > 
  > False... 

Sorry that you didn't recognize the tongue-in-cheek paragraph.

Intel had proposed somnething like this for a really cheap
mostly-software modem -- to which I thought "what a great
idea. For Intel. Dump a $9 part, and use 80% of the
CPU cycles of a $350 part."


  > > Knowing the baud rate, just sample the line every X microseconds.
  > 
  > I'm sorry to say: "You don't get it"...

Really? You must be very observant. Clairvoyant too? :-)

  > The trick is to get the data as fast as possible into the 
  > CPU. Without letting the CPU wait for it or slowing it 
  > down. So a good UART has a databus interface as wide as 
  > the CPU databus and busmastering.

The point is that getting the data into the CPU is only PART
of the problem. If, after getting the data into the machine,
the software has to, say, BE/LE swap, and align buffers etc.,
the advantage of high speed device<->cpu data transfer is
weakened.


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Philip K. Ronzone (RON-zone), extension 8300 ..................................
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