[sdiy] MIDI specifications

[Magnus Danielson]

From: Gene Stopp <gene at ixiacom.com>
Subject: RE: [sdiy] MIDI specifications
Date: Thu, 17 Apr 2003 09:00:28 -0700

> 
> >Oooo.... he said "link layer"... so there's
> >still people out there that believes in the
> >ISO OSI layering crap? (The OSI layering
> >caused more headache than it solved, the
> >OSI degeneration with the IP world leaves
> >even more to be desired.)
> 
> OSI-speak is a hard habit to break! Especially with so many mixed-opinion
> co-workers. But one look at a detailed OSI-model layer chart will tell you
> that something went wrong somewhere!

I've found that they cause more confusion then clarity in the broken way they
are interprented. The IP people for instance invent all kind of strange stories
in order to avoid saying that you break the layer principle. For instance, BCP-4
uses TCP (a layer 4 protocol) for its transfer sessions (actually layer 5) but
since it obviously provides a layer 3 service (doing the *actual* routing so
that the IP _forwarding_ has propper routing tables) they keep saying that the
TCP traffic can be "emulated" within layer 3 without being in layer 4, all this
is the bullshit people invent in order to make the layering rules still hold,
while everyone knows it's the same TCP implementation being in use. They also
claim that ATM is a layer 2 system, when it clearly has a end-to-end property
over the ATM network. Then you have all this layer 2 - switches, layer 3 -
routers bullshit, it is still switching mechanisms. The real braindamage is
"IP over Fibre" which is all marketing bullshit, it simply doesn't work that
way and then I know my way around that field pretty well. You simply can't do
IP over staight fiber, you need something there. The marketing bullshit is just
a way to bias your opinion towards a certain product. All the marketing bullshit
out there in network land is just like what we see for music and hifi gear.
Not selldom I would even expect that marketing guys have just shifted industry.

> >Also, you where incorrect on another thing,
> >in RS-232 you actually have threelevels, and
> >if you don't understand this you won't easilly
> >grip why turned of equipment causes other
> >equipment to malfunction. 0V is the "break"
> >level, having a totally distinct meaning from
> >that of logical high and logical low. In MIDI
> >there is fortunatly only two levels. However,
> >three-level signals make the world tick (PDH
> >tends to use it, besides all those RS-232
> >stuff).
> 
> Arrgh - I forgot about Break! The <ctrl><alt><del> of the RS-232 world!

Exaktly!

> Notice that there is still a Break key lingering on your PC keyboard, up by
> the Scroll Lock key. Kind of like the way we still call Enter "Carriage
> Return".

I thougth it was "Line Feed"? ;O)

If you run Windows it's both, just to be sure it was right (which it wasn't).

> Yes MIDI is free from many of these worries, it does what it needs to with
> minimum hassle and some shorcomings.

Instead it follows another tradition, it has invented it's own shortcommings!

> If I said that MIDI channel messages are "data plane" and MIDI system messages
> are "control plane", would you get mad at me? :)

Actually no. As long as you mention that they share the same transmission
network through asynchronous multiplexing ;O)

Cheers,
Magnus - deals with both transmission, control and management planes