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MPX 1 V1.10 MIDI Implementation Details
Parameter Data (Bytes 10-393)
The MPX 1 can assign algorithms with different parameters to a single effect block. For example, the Pitch
effect can be a detuner with 4 parameters, or a dual pitch shifter with 5 parameter. In addition, the third
and fourth parameters for the detuner are 1-byte parameters while the third and fourth parameters for the
pitch shifter are 2-byte parameters. In both cases, the actual data is stored in the same 32 byte section
of the dump called "pitch effect data". A table of Parameter Type numbers with a table of pointers to the
data structures is used to get information about any parameter whose Parameter Type number is known.
Parameter Type numbers
#define NOTE_PARAM 0x002C
#define MIX_PARAM 0x002D
#define LEVEL_PARAM 0x002E
For each algorithm in the system (a total of 61), there is a table containing the Parameter Types used by
the algorithm. For example:
Detune (M) Parameter Types
0x002D - Mix
0x002E - Level
0x003B - Tune
0x003D - P Dly
To edit a parameter, a pointer is initialized to the beginning of the 32-byte effect data block. This 32-byte
data block is treated as an array of bytes. In order to access the target parameter the offset into this 32-
byte array must be calculated. This is done by determining the number of bytes used by each of the
parameters preceding the parameter you want to edit. This is accomplished by walking through each of
the parameter types, in the algorithm's Parameter Type table and using the Parameter Type number to
access the parameter data structure to determine the number of bytes used. The pointer to the 32-byte
effect data block is then incremented by the number of bytes used by this parameter. When the process
is complete the pointer is left pointing at the target parameter's data.
For example, in the "Detune (M)" effect, "Tune" is the third parameter. After a pointer is initialized to the
beginning of the pitch "32 byte parameter data" array, it must be incremented past the first and second
parameters' data to get to the "Tune" data.
pitch parameter data:
0x64 - Mix
0x00 - Level
0x0A - Tune
0x01 - Tune Option
0x00 - P Dly
0x00 - unused
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table of pointers to structures
&Note_param,
&Mix_param,
&Level_param,
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