[Elecraft] Re: What's wrong with Serial

[Ian Stirling]

On Monday 19 June 2006 22:53, Ron D'Eau Claire wrote:

> As far as I know, there is NO such thing as a "RS232 cable".

 My several Amigas have a 25 pin 'serial' port.
There is also +/- 9v AC on a couple of pins to
power external equipment. It's welcome:
 I designed my own midi interface using +9 AC
to power it.

  An important point about RS-232, COM ports,
/dev/cuad0, /dev/ttyS0 .. whatever, is that the
serial data timing can be very accurately known:
the time taken for a micro to load to the data
registers and send the data can be used in real time
control. At 115200 bits per second, a byte takes
less than 100 microseconds to propagate.
  Midi is such a real time control and it uses the
very modest speed, by today's standard, 31250 bps.
  USB can't guarantee such timing accuracy for
control purposes - witness the mess with USB midi
equipment that had 80 milliseconds delay before
hearing a sound - fine if a printer doesn't start
in that time but completely useless for real time
music multitracking.
  A klutz was required, such as Steinberg's ASIO.
Even so, USB still can't compete with a 23 year old
standard at 31250 bps for real time midi.
  There is no USB on my Kurzweil PC2R. Present are
midi in, out and thru, analog and 24 bit digital
sound out: it's professional equipment.

  There's nothing wrong with Serial except that
most consumers don't need it, and unfortunately,
those who could use it are finding it scarce on
modern equipment due to market forces.

Ian, G4ICV, AB2GR, K2 #4962
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