Lexicon MPX 1 V1.10 - MIDI IMPLEMENTATION DETAILS Midi Implementation Manual page 30

Lexicon
The routine sets up a second pointer to the array of Parameter Type for the Detune (M) algorithm and
accesses the structure for the first parameter, Mix.
Detune (M) Parameter Types
0x002D - Mix
0x002E - Level
0x003B - Tune
0x003D - P Dly
The Mix structure shows that it is a one byte parameter so the data pointer is incremented once.
pitch parameter data:
0x64 - Mix
0x00 - Level
0x0A - Tune
0x01 - Tune Option
0x00 - P Dly
0x00 - unused
The Parameter Type pointer is incremented to get the Parameter Type of the second parameter.
Detune (M) Parameters Types
0x002D - Mix
0x002E - Level
0x003B - Tune
0x003D - P Dly
The second parameter's structure is accessed and reveals that it is the one byte parameter "Level".
The data pointer is incremented again and now points to the "Tune" parameter data.
pitch parameter data:
0x64 - Mix
0x00 - Level
0x0A - Tune
0x01 - Tune Option
0x00 - P Dly
0x00 - unused
Detune (M) Parameters "Types"
0x002D - Mix
0x002E - Level
0x003B - Tune
0x003D - P Dly
As the operating system for the MPX 1 displays a maximum of two parameters at once, two such pointers
are set up.
There are two ways an off-line system can build a Parameter Types list for a given effect's algorithm. One
approach is to request the Report Effect Parameters (18 hex) message which returns this list directly. A
more generic method of generating a list of Parameter Types for a given algorithm is to use the Parameter
Type (03 hex) message. The request for this message class takes the control address for a parameter
and returns the Parameter Type at that address. For example, "pitch" is at control address 0-0. The pitch
algorithm Detune (M) is at address 0-0-1. Detune (M) parameters are at addresses 0-0-1-0 through 0-0-
1-3. The Detune (M) parameter itself will tell you how many parameters it has from which you can request
the Parameter Type message for each parameter to build a local list with.
Once the Parameter Type number is known, the number of bytes used by the parameter can be derived
from the Parameter Description. There are two basic approaches to dealing with Parameter Descriptions.
One is to request the Parameter Description (04 hex) each time you have a Parameter Type number and
you need to know something about the parameter. The other approach is to build a database of parameter
descriptions locally and reference it whenever you need to find out something about a parameter. If disk
space and/or RAM space is available, the latter approach is preferable as it makes acquisition of
Parameter Descriptions a one time effort.
MPX 1 V1.10 MIDI Implementation Details
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