Midi Implementation; Overview; The Channel Byte; The Opcode Byte - Alesis MIDIVERB IV Service Manual

11.00 MIDI Implementation

OVERVIEW

All MidiVerb 4 system exclusive messages have the following format:
$F0 System Exclusive status
$00 $00 $0E Alesis manufacturer ID
$11 MidiVerb 4 ID
nn Channel
cc Opcode
dd Data
: :
: :
$F7 End of Exclusive

THE CHANNEL BYTE

For messages originating from the MidiVerb 4 the system exclusive channel will always be the same as the
standard MIDI channel, and can be adjusted by the user via the global utility functions. If the user has
enabled Omni mode the MidiVerb 4 will respond to system exclusive messages on ANY channel and transmit
on channel 1, just as it does for ordinary channel messages (note, controller, program change, etc.) when
Omni mode is enabled.
If a transmitting device such as a computer does not know the MIDI channel of a MidiVerb 4 it can use
transmit the MIDI universal system exclusive inquiry message with the channel byte set to $7F (ALL CALL).
The MidiVerb 4 will respond with a universal system exclusive identity message with the channel byte set to
the current MIDI channel (0-15). This is the recommended technique for closed loop systems as it allows
software programs to confirm the MidiVerb 4's software version and revision while it finds the channel.

THE OPCODE BYTE

Opcodes are divided into two categories: Requests and Dumps. The values for Request opcodes are closely
related to their corresponding Dump opcodes -- they are simply the Dump opcode with bit 6 set.
Only one of the Request opcodes has a data byte -- the Single Program request. The data byte specifies which
User Program (0-127) it is requesting.
Dump Request
Opcode Opcode
$00 $40
$01 $41
$02 $42
$03 $43
$04 $44
$05 None
SYSTEM INFO DATA
Alesis MidiVerb IV Service Manual
System Exclusive Format
Software Version 1.02
February 17, 1995
Function
Description
System Info
Program Table
Edit Buffer
All User Programs
Single Program
Store Program
Dump Message Size
(in bytes)
22
264
50
5384
51
9
15 03/05/99