[LAD] midi beat clock

[Pedro Lopez-Cabanillas]

On Saturday, February 20, 2010, Rui Nuno Capela wrote:
> On 02/20/2010 01:00 AM, Tim E. Real wrote:
> > On February 19, 2010 07:51:58 pm Rui Nuno Capela wrote:
> >> On 02/20/2010 12:40 AM, m.wolkstein at gmx.de wrote:
> >>> here the mbc specs.
> >>> midi beat clock defines the following real time messages:
> >>>     * clock (decimal 248, hex 0xF8)
> >>>     * tick (decimal 249, hex 0xF9)
[...]
> > It also transmits them. It also recognizes tick but doesn't use it.
> > From what I understand, tick is nothing more than a periodic 'keep alive'
> > signal, not a sync signal. I could be wrong though...
>
> this "tick" signal (0xf9) must be (is it?) some leftover from ancient
> midi times, if ever used effectively. i fail to recognize its use but
> being just, uh,... _undesirable_ noise:)
>
> i'll turn off

0xf9 is Undefined (Reserved), according to:
http://www.midi.org/techspecs/midimessages.php

Or the MIDI specification 1.0, which is embedded in many books, like this one:
http://books.google.com/books?id=S-T6a9OXwGQC&lpg=PA236&pg=PA234#v=onepage&q=&f=false

The "keep alive" message is 0xfe (dec. 254) Active Sensing. And by the way, 
here is another mirror of the Jeff Glatt's MIDI docs:
http://home.roadrunner.com/~jgglatt/
It is an useful site, because the official MIDI specification is not published  
online my midi.org, but it is not an official source. I would like to know 
the origin of this "tick" 0xf9 message. Is it an addition from some 
manufacturer?

Regards,
Pedro