When the MIDI spec was first developed, it wasn't foreseen that anyone would need more than 128 patches on a given module. (Back then, most didn't even have anywhere near that number of patches). So, the MIDI Program Change message was hardwired to have a limit of counting only from 1 to 128.
Later, modules with more than 128 patches came on the market. People needed some way of being able to switch to these extra patches, but which was still compatible with the old way of switching patches. The manufacturers adopted a scheme of arranging patches in "banks" (ie, groups of usually 128 patches). For example, the first 128 patches in a module may be "bank 1". The next 128 patches may be "bank 2". Etc. Theoretically, there can be up to 16,384 banks on a module.
The technique that the manufacturers adopted for MIDI control over patch changing is to have the musician first select the bank that contains his desired patch, and then select the patch within that bank. For example, assume that a musician wants to select the patch "Gungho" which happens to be the third patch in the second bank. First the musician would have to send one or two (depending upon how the manufacturer arranged patches into banks) MIDI messages to select the second bank (MIDI counts this as bank 1, since MIDI considers bank number 0 to actually be the first bank). Then, the musician sends a MIDI message to select the third patch (again, MIDI considers patch number 0 to be the first patch in a bank, so the third patch would actually be number 2). So, selecting a patch is a two-step (ie, 2 or 3 message) process. First, you send the Bank Select message(s) to switch to the desired bank. Then you send an ordinary Program Change message to select which one of the 128 possible patches in that bank you desire.
The Bank Select messages are actually MIDI Controller messages, just like Volume, Pan, Sustain Pedal, Wind, and other controllers. Specifically, the controller number for the "Most Significant Byte" (ie, MSB) of Bank Select is controller 0. The controller number for "Least Significant Byte" (ie, LSB) of Bank Select is controller 32. The data for these messages are the bank number you want to select. (Sometimes the MSB Bank Select is referred to as the coarse adjustment for bank, and the LSB Bank Select is referred to as the fine adjustment).
NOTE: We need to use 2 messages to contain the bank number because, due to MIDI's design, it's not possible to transmit a value greater than 128 in just one controller message. Remember that a bank number can go as high as 16,384, and you need 2 MIDI controller messages to send such a large value. But, since most modules do not have more than 128 banks anyway, these modules typically only use the MSB message (ie, controller number 0) to select bank, and ignore any LSB message (ie, controller number 32). So then, here are the two messages (in hexadecimal, assuming MIDI channel 1, and assuming that the module only uses the MSB Bank Select controller) to select that "Gungho" patch:
|B0 00 01||Switch to bank 2 (NOTE: only the MSB message needed)|
|C0 02||Switch to the third patch in this bank|
The patch doesn't actually change until the module receives the Program Change message. The Bank Select message(s) must precede the Program Change message. Otherwise, the module would select the third patch in whatever bank the module was currently set to. (In other words, when the module receives Bank Select messages, it doesn't change any patches. Rather, it simply notes what the "current bank" is, and any subsequent Program Change messages will switch to patches within that bank. What this also means is that you don't necessarily need to send Bank Select before every individual Program Change. If you're switching to a patch in the same bank as whatever patch you've currently selected, then you can omit the Bank Select messages since the module will then assume the same bank).
The following, real-world example concerns a Roland module. Before proceeding, you should read The architecture of Roland sound modules if you're unfamiliar with the way that Roland arranges Patches into "Banks".
Let's look at the JV-90 as an example. Look under the "MIDI Implementation" chapter of the manual. Follow the "Receive Data" section until you get to "Control Change" and "Bank Select". (The article Understanding the MIDI Implementation in your Roland manual helps guide you through this chapter of the manual). As is so typical of Roland, the company uses the MIDI spec in a clever way. Rather than using the data bytes of both the MSB and LSB messages "added" together to make up a single bank number, Roland sort of uses the MSB message to select the "component" that you wish to access, and the LSB message to select the bank within that component (ie, some components contain several banks, such as the factory patches in ROM).
Look at the following list: (Note that I'm using a fixed pitch font to line up the columns)
Bank Bank Program Media MSB LSB Change 80 0 1 - 64 Internal (ie, User custom presets in RAM) 80 0 65 - 128 Data Card 81 0 1 - 64 JV-90 Preset A (ie, factory patches on Voice Expansion) 81 0 65 - 128 JV-90 Preset B (ie, factory patches on Voice Expansion) 81 1 1 - 64 Preset A (ie, factory patches in ROM) 81 1 65 - 128 Preset B (ie, factory patches in ROM) 81 2 1 - 64 Preset C (ie, factory patches in ROM) 81 2 65 - 128 Preset D (ie, factory patches in ROM) 82 0 1 - 64 Data Card 83 0 1 - 128 PCM Card 84 0 1 - 128 Expansion Board (ie, factory patches on Wave Expansion) 84 1 1 - 128 Expansion Board (129 - 256)
Let's say that you want to select the third patch on the factory presets "B" group. Look at "Preset B". In order to select from these patches, first you must send an MSB Bank Select with the decimal value 81 (ie, hexadecimal 51). Next, you must send an LSB Bank Select with the value 1. Finally, you can send a Program Change. The patches in this bank are numbered 65 to 128 (ie, the first patch in the "Preset B" is number 65 -- actually it is 64 in our Program Change message since we always subtract 1 to account for MIDI assuming 0 as the first patch in a bank). So the third patch in Preset B is #67 (really 66, or hexadecimal 42). Here are the 3 messages (assuming MIDI channel 1):
|B0 00 51||MSB (Coarse) Bank select|
|B0 20 01||LSB (Fine) Bank select|
|C0 42||Program Change|
Let's select the first patch in User RAM (ie, "Internal" as Roland calls it in the above chart). We need an MSB Bank Select of 80 (hexadecimal 50), an LSB Bank Select of 0, and then a Program Change to patch 1 (actually 0) since the patches are numbered 1 to 64 here.
|B0 00 50||MSB (Coarse) Bank select|
|B0 20 00||LSB (Fine) Bank select|
|C0 00||Program Change|
Of course, if you subsequently want to select another patch in this same bank, then you can skip sending the 2 Bank Select messages. After all, "User RAM" is now the current bank.
Although most Roland sound modules use Bank Select controller in ways similiar to the JV-90, your unit may have different components and different bank numbers used to select them. You need to look up the appropriate chart in your Roland manual. It will be found in the "MIDI Implementation" chapter, under the RECEIVE DATA main section, CONTROL CHANGE subsection, and "Bank Select" sub-subsection.
Some sequencer programs allow you to setup an "instrument definition" wherein you simply enter the above 3 messages and then specify the name of the patch. For example, maybe this patch is called "Gungho". You can tell your sequencer that whenever you select "Gungho" from a list of patch names, the sequencer will then automatically insert the above 3 messages into your track at some specified point where you want to switch to the "Gungho" patch. It's a lot easier to setup that instrument definition once, detailing the messages to insert for each patch name, and then from there, only deal with selecting patch names from some list rather than needing to remember what Bank Select and Program Change messages need to be inserted. But of course, in order to create such a definition, you need to understand the above (once anyway -- and then you can forget about it all -- after the nightmares subside).
For example, you can go into CakeWalk's Settings->Assign Instruments menu item, and click on "Define Instruments" to create a new instrument definition for your MIDI module. Unfortunately, I think that CakeWalk's instrument definition is most unintuitive and convoluted because you have to first dig your way down to the "Define names" dialog box, skipping a whole dialog of settings, in order to enter all the banks of patch names prior to even defining what sort of bank select your module uses and what those banks are. This "bottom up" approach may save some time if you're dealing with a module whose banks tend to include a lot of duplicate patches, but it's really a pain for modules whose banks do not contain duplicate patches. I'd prefer to first choose the "bank select method", and then have CakeWalk guide me through the naming/numbering of a bank, immediately followed by each patch name/number in that bank, and so on for however many more banks there are. Worse, it appears that you have to enter the Banks by editing a rather freeform text file. For this reason, the creation of CakeWalk instrument definitions is a perilous and difficult undertaking for all but the most patient and experienced.
Once you have an instrument definition, you can insert a Bank Select (MSB and LSB) and Program Change in a CakeWalk track simply using the Insert menu's "Bank/Patch change".
The very first Bank Select and Program Change events, if they appear before any note events in a track, are automatically extracted by CakeWalk and used to set the "Bank" and "Patch" fields in CakeWalk's track display. So, you use these two fields to enter your values for any initial Bank and Program Change at playback start. Then, if you want to change the Bank and/or Patch somewhere in the middle of the track (ie, after notes have already been played, you'll have use CakeWalk's Insert menu to insert "Bank/Patch change". Choose a Bank and a Patch, and enter the desired time where it should be inserted, and CakeWalk will insert the Bank Select and Program Change events in the track at that desired point. You should see these shown in the Event List. If you don't have a CakeWalk instrument definition file for your MIDI module, then you'll need to manually insert the desired Bank controller events yourself using Insert menu's "Series of Controllers". Do this once to choose "Bank Select" controller (ie, the coarse, or MSB one) and its desired Value and Time. (If your unit also requires the LSB or "fine" value for Bank Select, you'll need to repeat this to choose "Bank Select (fine)" controller and set its value/time). Then use the "Bank/Patch change" just to pick out one of the 128 patches in the bank.