The data turned ON or OFF by this function consists of the following:
Initial touch response data. Although the DX21 does not have key velocity sensitivity (keyboard touch response), its tone generator is capable of receiving key velocity information from an external keyboard which has this capability.
(b)MODULATION WHEEL: Modulation wheel position.
(c)BREATH CONTROLLER: Breath controller pressure.
(d)PORTAMENTO FOOT SW: Portamento footswitch on/off status.
(e)PROGRAM CHANGE: Voice memory selection.
(f)DATA ENTRY CONTROL: DATA ENTRY control position. Transmission only.
(g) DATA ENTRY SW: | DATA ENTRY +1 and |
| mission only. |
Pitch bend, sustain switch and “all keys off” status data are transmitted whether this function is ON or OF.
NOTE: 
The above MIDI data is generally common to all keyboards and equipment compatible with the MIDI system. Due to differences in the features provided by some manufacturers, however, complete compatibility can not be guar- anteed.
A7: SYSTEM INFORMATION
This function turns transmission and reception of MIDI SYSTEM EXCLUSIVE INFORMATION data ON or OFF. The DATA ENTRY ON and OFF buttons are used to turn this function ON or OFF. MIDI SYSTEM EXCLUSIVE INFORMATION consists of voice parameters and related data which is transmitted by the BULK TRANSMIT function (A8) described below. When this function is ON voice parameter changes made in the DX21 EDIT mode are transmitted in real time.
A8: BULK TRANSMIT
This function permits transmission of "32 Bulk Data”. That is, the data pertaining to the 32 voices contained in the DX21 RAM voice memory. This data could be transmitted, for example, to the RAM voice memory of another DX21.
When this function is called the LCD will read "Midi Transmit ?". Pressing the DATA ENTRY YES button then begins actual transmission of the data. During transmission the LCD will go blank. Transmission takes about two seconds.
NOTE:
System exclusive communication data is only useable with compatible Yamaha MIDI equipment.
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