Casio DH-100 Digital Horn Midi Sax

images via this auction

"The Casio DH-100 is a monophonic MIDI instrument with 6 tone’s : Saxophone, Trumpet, Synth, Reed, Oboe, Clarinet and Flute.

All of the tone's timbre changes depending on the breath control from the mouth piece. The Horn is especially useful as a MIDI controller - as the breath control message is produced from the MIDI out allowing expression to be added to keyboard performances. With the use of MIDI-ox [downloadable from the web] it is possible to filter out the note message and use the horn as a breath controller which produces only the breath control necessary to alter the timbre of other instruments which respond to breath control.

The horn also has a portamento control - and produces this MIDI message - to produce glide between notes and a rear key which alters the octave.

It is possible to produce alternative fingering for the DH-100 by holding down the portamento control upon switching on. Then the instrument can cover a wider range of octaves.

These instruments can suffer from a failure, causing it to "squeak" - but this is repairable for about 50p by adding a capacitor. This has been replaced. The details are at [homepage.ntlworld.com/paul.fox4/casiofixes.htm].

Fingering
The fingering method supports 2 modes - one of which is a conventional wind instrument mode with the octave being changed from a key on the rear of the instrument. The other is brought about by holding down portamento whilst switching on and allows a wider range of notes and uses a CASIO fingering mode to create the notes and some of the keys to change octave

Voices
The 5 voices respond to the breath control from the mouthpiece whilst the breath control is switched to the ON position but the mouthpiece can be switched OFF and breath control is no longer active in creating any sound. The voices are all monophonic and respond dynamically to breath, varying the timbre and loudness in response to the mouthpiece. Portamento can be added creating a glide effect between notes.

MIDI
The MIDI OUT terminal supplies control information for linking to other synthesizers and supports the breath control, though this is sent out as after pressure information. In order to get breath control on instruments such as Yamaha DX series it is necessary to alter the after pressure to a breath control signal - this can be done with a PC and MIDI-ox which is obtainable from MIDI-ox.com."

Update via thegoodbutcher in the comments:
"These things are quite modifiable, too! http://home.earthlink.net/~kerrybradley/id5.html"