MPU-401 Documentation

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By Julien Pierre

Contents

About Theta Band Software

Theta Band Software, LLC was founded in October 1997 by a team of multimedia and internet software experts.

Theta Band Software is committed to delivering next-generation multimedia and internet applications and system software for personal computers.

Theta Band Software products will primarily target IBM's OS/2 Warp operating system family, ensuring that OS/2 users will always be the first and best supported by our technologies and products. Versions for other platforms will be released with the intent of supporting our OS/2 customers.

After all, we could write only Windows software, but where's the fun in that?

Please visit the Theta Band Software website at http://www.thetaband.com

About MM Pack 1.0

Theta Band Software proudly announces the MM Pack - a collection of utilities to enhance OS/2 multimedia. But before we can tell you what the MMPack does, you need to know some basics about multimedia and OS/2.

What is MMPM/2?

MMPM stands for "Multi Media Presentation Manager." It's just the name of the multimedia subsystem of OS/2.

What exactly is multimedia?

The term "multimedia" is a combination of words "multi" and "media". "Media" refers to things like digital audio, MIDI, or video. Multimedia is the process of combining two or more of these media together, hence the "multi" in "multimedia". Technically speaking, playing a wave file by itself is not multimedia, but playing a video file that has an audio track is multimedia. However, few people recognize the distinction, so anything that has to do with audio or video is considered multimedia.

What does OS/2's multimedia subsystem do?

MMPM/2 provides two core functions:

  • Playing and recording of different types of media, like digital audio, video, and MIDI
  • Synchronization between multiple "streams" of these media, so that when you play a video, the audio track is synchronized (for example).

This is just what the core of MMPM/2 does. Most of the interesting work is handled by a variety of "plug-ins" that allow it to understand the different types of media as well as the different types of hardware that you need in order to play or record the media. MMPM/2 supports plug-ins that ...

  • understand the differences between file formats, such as an AVI movie vs. a QuickTime movie. These plug-ins are called "input/output procedures", or IOProcs.
  • understand the differences between data encodings, such as the Intel Indeo AVI format vs. the Microsoft Video for Windows AVI format. These plug-ins are called "compressors/decompressors", or codecs.
  • understand the difference between hardware devices, such as a SoundBlaster 16 vs. an ESS 1868. These plug-ins are called device drivers.

IBM provides several plug-ins with OS/2, but not enough. In addition, some of the existing plug-ins don't always work right, or work the way you want them to. For instance, we've all had problems installing device drivers, or maybe there's a MIDI file that works great in Windows but won't work in OS/2. Or maybe you'd like to be able to play two wave files at once. This is where our MMPack comes in.

What will Theta Band Software's MMPack do for me?

The goal of the MMPack is to fill in all of these holes in MMPM/2. It is a collection of ioprocs, codecs, device drivers, and other utilities which bring out the true power of MMPM/2, and make multimedia under OS/2 more useful and, more importanly, more enjoyable.

MMPack 1.0 includes the following software:

  • MMCHECK - This is a utility that checks your MMPM/2 installation (i.e. MMPM2.INI) for errors or suspicious settings. If it finds any, it will tell you what they are, so that you can fix them.
  • MPU-401 Driver - This is a replacement for IBM's MPU-401 driver, which is used to MIDI support for a number of sound cards, including sound cards that use the Crystal Semiconductor drivers. Enhancements over IBM's driver include:
    • fixes for Warp 3
    • SMP compatibility
    • better hardware compatibility
    • DOS sharing
    • and more!
  • NPDSMI 2.0 - An enhancement over the free DSMI Netscape plug-in, this new version supports compressed (zip and gzip) module files.

About the MPU-401 audio device driver

The Theta Band Software MPU-401 audio device driver is an OS/2 device driver that provides MIDI playback and recording support. It supports both MMPM/2 and RTMIDI.

This package is a replacement for the MPU-401 driver from IBM and Crystal Semiconductor. It provides a complete feature superset over these two drivers.

Help for Selecting Number of Adapters

The MMPM/2 installation procedure assumes that a device driver can only support one adapter or one device. Therefore, if you have more than two of the same adapter in your computer, you must install two copies of the device driver. Specifying the number of adapters in the computer is the same as specifying how many copies of the device driver need to be installed.

The MPU-401 driver behaves somewhat differently from most audio device drivers.

First, the driver does not support adapters per se. Rather, it supports MPU-401 compatible devices, and a single adapter card can have more than one of these devices. To the MPU-401 driver, these multiple devices will appear as if they exist on separate adapter cards.

Second, a single copy of the MPU-401 driver can be configured to support multiple devices. This breaks the one-to-one ratio between the number of drivers installed and the number of physical adapters (or in this case, devices) in the computer.

However, the default installation tells the MPU-401 driver to locate only one MPU-401 device. This maintains the one-to-one ratio that makes MMPM/2 happy. This default is settable by the Number of devices to autodetect option.

When the base I/O address is manually selected during install (i.e. it is not set to "autodetect"), the driver will only support one device, and the Number of devices to autodetect option is ignored. If you wish to manually specify the I/O address for more than one port, you must either install multiple copies of the driver, or manually add /P switches on the command-line.

If you select "autodetect" for the base I/O address, each copy of the driver, at boot time, will attempt to locate and provide support as many as nine MPU-401 devices (although the default behavior is to locate only one). Of these, only the "first" will be available to MMPM/2, since MMPM/2 expects there to be only one MIDI device for each copy of the driver installed. The remaining devices will only be visible to RTMIDI (the real-time MIDI subsystem).

If you select to install zero devices, then you will remove support for all MPU-401 devices that have been previously installed by MMPM/2.

Help for selecting MPU-401 values

On this screen, you specify the values that you want to use with your MPU-401 Adapter. To get help for these options, view the table of contents for this help panel by selecting Options->Contents, pressing Ctrl-C, or selecting from the list below.

If you choose Close from the system menu, the selected values are set back to the default values.

Select Ok to save the selected values and continue.

  • Base I/O Address
  • Interrupt Level
  • Number of devices to autodetect
  • MMPM/2 TIMER0 resolution
  • I/O and IRQ boot-time checking
  • Resource Manager IRQ Usage
  • Resource Manager I/O Usage
  • Resource Manager I/O address width
  • Enable DOS hardware sharing support

Base I/O Address

This field allows you to select the base I/O address for the MPU-401 device. Specify either one of the 19 address, or select "Autodetect". If "Autodetect" is selected, the driver will, on every boot, search all 19 addresses for an MPU-401 device. Each device found will be registered with RTMIDI. The first device found will be used with MMPM/2. Use the Number of devices to autodetect option to specify how many devices the driver should look for.

The default is "Autodetect". The other choices are 330, 300, 332, 334, 336, 200, 210, 220, 230, 240, 250, 260, 270, 310, 320, 340, 350, 360, and 370.

If you install only one copy of the device driver (i.e. you specified that you have only one MPU-401 installed), then you should generally use Autodetect unless:

  • The first device is not the device you want to use with MMPM/2 (applicable only if the Number of devices to autodetect option is set to "All of them").
  • You know that autodetection will cause problems.
  • You are using the /O:NOCHECKIO option. A boot error will occur if /O:NOCHECKIO is combined with I/O autodetection, and the driver will not load.

The /O:NOCHECKIO option is specified if you select "Check only IRQ" or "Check neither" under the I/O and IRQ boot-time checking section.

This settings corresponds to the /P command-line parameter. Base I/O address autodetection is enabled if there are no /P parameters specified on the command-line.

Interrupt Level

The Interrupt Level is used for MIDI recording, which is a feature of RTMIDI. In order for MIDI recording to work, the driver must receive an "interrupt" whenever the hardware has MIDI data.

This field allows you to select the interrupt level (IRQ) for the MPU-401 device. It also allows you to specify the IRQ-less option, which tells the driver to use TIMER0 instead of a hardware interrupt. IRQ-less recording should only be used if you cannot use a normal Interrupt level.

If the Base I/O Address is set to Autodetect, the IRQ must also be set to Autodetect (unless you specify IRQ-less recording). A boot error will occur otherwise, and the driver will not load. Also, if IRQ Autodetect is selected, then the /O:NOCHECKIRQ flag must not be specified. Doing so will also cause a boot error.

IRQ autodetection is generally safe, safer than base I/O autodetection. However, there can be cases when the IRQ is not detected. If this is the case, the base I/O addresses and the IRQ levels can be specified.

The default is "Autodetect". The other choices are 3, 4, 5, 7, 9, 10, 11, 12, 14, 15, and "None". "None" means to use IRQ-less recording. Note that the /O:NOTIMER0 option does not affect IRQ-less recording. In other words, if you select "None" and /O:NOTIMER0, TIMER0 will still be used for MIDI recording.

The /O:NOCHECKIRQ option is specified if you select "Check only I/O" or "Check neither" under the I/O and IRQ boot-time checking section.

This settings corresponds to the /I command-line parameter. IRQ autodetection is enabled if there are no /I parameters specified on the command-line.

Number of devices to autodetect

This setting is ignored if I/O port autodetection is not enabled.

When this setting is set to the default of "Only One", the driver will stop searching after it has found one MPU-401 device. This allows the autodetection routine to conform to MMPM/2's requirement that each copy of the driver represents only one device.

For example, say that there are three MPU-401 devices in the computer. To get MMPM/2 to recognize all of them, three copies of the driver would need to be loaded.

MMPM/2 TIMER0 resolution

The MPU-401 driver uses the UART (a.k.a. dumb) mode of the MPU-401 interface, which is the only mode that the majority of audio cards support. This mode does not provide timing services, which are needed by an MMPM/2 MIDI driver for MIDI playback. Therefore, the MPU-401 driver uses the high-resolution timer driver, TIMER0.SYS, for timing purposes. If necessary, the MPU-401 driver can use the system timer, but the timing accuracy may not be acceptable.

MMPM/2 relies on the device drivers for timing information, so this setting affects MIDI playback through MMPM/2 only. RTMIDI, on the other hand, performs all timing internally, so if you do not plan to use this driver with MMPM/2, then this setting should be set to "Never use TIMER0".

This setting allows the user to specify if TIMER0.SYS should be used, and if so, at what resolution. A higher resolution means less time passes between ticks. The higher the resolution, the more accurate the playback will be, but the more demanding this driver will be on system resources. The default value of 2 milliseconds provides excellent resolution without noticeable load under normal circumstances. 1ms is generally too fast, and should only be used on very fast computers if necessary.

If "Never use TIMER0" is specified, then the MPU-401 driver will use the system timer, which runs at 31.25 milliseconds (32 ticks per second). If "Never use TIMER0" is not specified, then the driver will use TIMER0.SYS if it is available. If it is not, it will switch to the system timer automatically.

This settings corresponds to the /R command-line parameter.

I/O and IRQ boot-time checking=

By default, the MPU-401 drivers checks for the existance of MPU-401 hardware at each boot. With certain sound cards, such as those that use a DOS application to initialize the board, the hardware is not visible until after the driver has loaded. This option allows you to specify if the driver should check for actual hardware at boot time, or if it should simple assume that the hardware is there.

The options are to check both the base I/O address and the IRQ, to check only the base I/O address, or to check neither. Since a base I/O address is needed to check for an IRQ, it is not possible to check for an IRQ but not a base I/O address.

If I/O autodetection is enabled, then I/O checking must also be enabled. Similarly, if IRQ autodetection is enabled, IRQ checking must also be enabled. A boot error will occur if these requirements are not met, and the driver will not load.

Note that if IRQ checking is disabled, and the IRQ is not specified, then there will be no IRQ assigned to the MPU-401 device, and MIDI recording will not be possible.

This settings corresponds to the /O:NOCHECKIO and /O:NOCHECKIRQ command-line parameters.

Resource Manager IRQ Usage

Resource Manager (RM) is a subsytem which allows device drivers to register which hardware resources (I/O addresses, IRQs, DMA channels, etc) are used and how they are used. This setting controls if and how the MPU-401 driver registers the IRQs it uses.

Normally, a device driver would first ask RM if any of the resources it plans to use are already allocated by another driver. The allocated resources are then marked as unavailable, and if there are not enough remaining resources, or if the hardware cannot be found at these resources, the driver terminates with an error message. Otherwise, the driver claims the resources it needs and reports them to RM, so that the next device driver won't touch them. The reasoning behind this process is that only one device driver interacts with a particular resource.

The MPU-401 driver is different from other drivers in that it can be used in conjunction with other drivers to communicate to the same hardware. Although this works in theory, in practice there can be conflicts. Caveat emptor. See the section titled Using the MPU-401 driver with other audio device drivers for more information.

By default, the MPU-401 driver asks RM if a resource is available before it touches it, and for each resource it finds, it makes an exclusive claim with RM for that resource. This behavior will generally prevent the driver from working with other device drivers. Note that the intent behind RM is to prevent multiple device drivers from talking to the same hardware, so by circumventing the MPU-401 driver's RM checks, you are also circumventing the protection that RM provides.

To completely bypass RM, select the "None" option. Alternatively, the driver can still interact with RM, but on a level more relaxed than "Exclusive". "Shared" means that two drivers can use the same resource simultaneously. "Multiplexed" means that the two drivers have a private interface where they switch-off access to the resource. Note that the MPU-401 driver has no such private interfaces, so the use of "Shared" or "Multiplexed" should be chosen based on which interacts better with the competing device driver.

This settings corresponds to the /O:SHAREDIRQ, /O:MULTIIRQ, and /O:NORMIRQ command-line parameters.


Resource Manager I/O Usage

See the discussion on Resource Manager IRQ Usage for an explanation of Resource Manager. This setting is like the RM IRQ usage setting, but it applies to I/O addresses instead.

This settings corresponds to the /O:SHAREDIO, /O:MULTIIO, and /O:NORMIO command-line parameters.

Resource Manager I/O address width

An I/O address is a 16-bit quantity, so there can be 65,536 of them. However, most devices only check (decode) the lower 10 bits of the address, thereby ignoring the upper 6 bits and making all addresses which have the lower 10 bits in common behave as if they were identical.

For instance, consider such a device configured to use I/O address 0x330 (0000 0011 0011 0000 in binary). Any I/O operations to address 0x330 will go to this device. However, since it only decodes the lower 10 bits, I/O operations to address 0x1330 (0000 0111 0011 0000) will also go to this device. Same for 0x2330, 0x3330, 0x4330, and so on. So to properly avoid conflicts with other devices, the driver would have to register all 64 variations of 0x330.

RM has provisions to handle such devices. When an I/O address is registered with RM, the address width (number of significant bits) is also included. So if a 10-bit device registers address 0x330, a 16-bit device cannot register address 0x1330 later. Note that a 10-bit device cannot register 0x1330 ever, because 0x1330 has 11 significant bits.

The default address width depends on whether the computer uses the ISA (Industry Standard Architecture) system bus or the MCA (MicroChannel Architecture). Almost every ISA device decodes only 10 bits, but almost every MCA card decodes all 16. So on an ISA computer, the default address with is 10 bits, and on an MCA computer, the default width is 16 bits.

This setting allows you to change the address with for all devices. Note that you cannot specify the address width for each device. If you have a combination of 10-bit and 16-bit MPU-401 devices in your computer, you will need to load two copies of the driver, one for all 10-bit devices, and the other for all 16-bit devices.

This settings corresponds to the /O:10BITS and /O:16BITS command-line parameters.

Enable DOS hardware sharing support

Tells the driver to attempt sharing the hardware resources (I/O ports and IRQs) with DOS and Windows MIDI applications.

This option corresponds to the /O:AUDIOVDD parameter. More information is available there.

Command-line Parameters

This section describes all of the possible command-line parameters for the MPU-401 driver. The installation procedure allows you to specify most of these options. Manual customization of the command-line may be necessary for some features.

Parameters are separated by one or more blank spaces. They are all in the form of /X[n][:qualifier]

where


   / is a required forward-slash that precedes each parameter
   X is the parameter itself, a single letter of the Roman alphabet
   [n] is the port number, an decimal digit between 1 and 9 required by some parameters
   [:qualifier] is the qualifier for the parameter, a string or number required for some parameters 

Parameters that require port numbers are used to specify a setting for a particular MPU-401 device. Remember, the MPU-401 driver supports up to nine independent MPU-401 devices.

The interpretation if the qualifier depends on the parameter. For example, the /N parameter interprets the qualifier as an ASCII string, the /P parameter interprets it as a hexadecimal number, and the /I parameter interprets it as a decimal number.

This list shows what each of the symbols mean:


   n is a decimal digit from 1 to 9 indicating the port number
   ddd is a decimal number greater than zero
   hhh is a hexadecimal number greater than zero
   sss is an ASCII string 

Here is the list of all command-line parameters:

/P /I /N /R /V /O:LONGNAME /O:QUIETINIT /O:NORMIO /O:SHAREDIO /O:MULTIIO /O:NORMIRQ /O:SHAREDIRQ /O:MULTIIRQ /O:NOCHECKIO /O:NOCHECKIRQ /O:NOTIMER0 /O:10BITS /O:16BITS /O:ONLYONE /O:AUDIOVDD

/Pn:hhh - Base I/O (Port) Address

This parameter specifies the base I/O address for given port. For example, /P5:208 says that device #5 is located at I/O address 208 hexadecimal.

This parameter can be set with the Base I/O Address option.

/In:ddd - Interrupt Level

This parameter specifies the IRQ level for the given port. The IRQ level must be between 1 and 15. For example, /I2:10 says that device #2 uses IRQ level 10 decimal.

This parameter also specifies the IRQ-less MIDI recording option. To select IRQ-less recording, set the IRQ level to 0. For example, /I2:0 says that device #2 should use TIMER0 for recording.

This parameter can be set with the Interrupt Level option.

/N:sss - Device Driver Name

This parameter takes a string, up to 7 characters in length and terminated by a $ (for a maximum of 8 characters including the $). The default is "MPU401$". If you install more than one copy of MPU401.SYS, each one must have a different name. MINSTALL takes care of this for you.

This parameter cannot be set by any option. To change the default value, CONFIG.SYS must be manually edited.

/R:ddd - TIMER0 Resolution

Resolution of MMPM/2 timing. If the high resolution timer (TIMER0.SYS) is installed, this parameter tells the MPU-401 driver what resolution to use (where yyy is the number of milliseconds) when playing MMPM/2 MIDI streams. Default is two milliseconds.

This parameter can be set with the MMPM/2 TIMER0 resolution option.

/O:sss - Options

These options enable or disable certain features of the MPU-401 driver. The following sections list the possible values for sss and their meanings.

LONGNAME - Long RTMIDI Names

Long name support. If specified, /L directs the driver to include the base I/O address and the IRQ in the instance name for RTMIDI Type A registration. For example, without /L the instance name might be "MPU-401 #1". With /L, it would look like "MPU-401 #1 (I/O=0330, IRQ=05)". This option, like the /N option, must be specified if more than one copy of MPU401.SYS is loaded.

QUIETINIT - Ignore Initialization Errors

Tells the driver to ignore errors when an OS/2 MMPM/2 application wants to play a MIDI file. This option may be necessary for some audio adapters.

NORMIO - Do not check/register I/O addresses with RM

Tells the driver not to check or claim I/O address with the Resource Manager.

This parameter can be set with the Resource Manager I/O Usage option.

SHAREDIO - Check/register I/O addresses as Shared

Tells that driver to use the Shared attribute when checking and claiming I/O addresses with the Resource Manager.

This parameter can be set with the Resource Manager I/O Usage option.

MULTIIO - Check/register I/O addresses as Multiplexed

Tells that driver to use the Multiplexed attribute when checking and claiming I/O addresses with the Resource Manager. Frequently used when the MPU-401 driver shares the same hardware with another driver, such as SB16D2.SYS.

This parameter can be set with the Resource Manager I/O Usage option.

NORMIRQ - Do not check/register IRQs with RM

Tells the driver not to check or claim IRQs with the Resource Manager.

This parameter can be set with the Resource Manager IRQ Usage option.

SHAREDIRQ - Check/register IRQs as Shared

Tells that driver to use the Shared attribute when checking and claiming IRQs with the Resource Manager.

This parameter can be set with the Resource Manager IRQ Usage option.

MULTIIRQ - Check/register IRQs as Multiplexed

Check/register IRQs as Multiplexed. Tells that driver to use the Multiplexed attribute when checking and claiming IRQs with the Resource Manager.

This parameter can be set with the Resource Manager IRQ Usage option.

NOCHECKIO - Do not verify I/O addresses

Tells the driver not to verify whether an MPU-401 device exists at the I/O addresses specified by the /P switches. Use this option when the sound card is initialized after the driver is loaded, e.g. by a DOS application. When this option is specified, the /O:NOCHECKIRQ option is implied.

Understand that this parameter tells the driver not to check whether the specified I/O port exists or whether the hardware at that I/O port is functioning. Therefore, it is your responsibility to make sure that the I/O port specified with the /P option is correct and that the hardware is functioning. Otherwise, when an application attempts to use the hardware, it will receive an error message.

If you want the MPU-401 driver to also ignore the hardware when an application requests it, specify the /O:QUIETINIT option.

This parameter can be set with the I/O and IRQ boot-time checking option.

NOCHECKIRQ - Do not verify IRQs

Same as the /O:NOCHECKIO option, except it applies to the IRQ level.

Understand that this parameter tells the driver not to check whether the specified IRQ exists or whether the hardware at that IRQ is functioning. Therefore, it is your responsibility to make sure that the IRQ specified with the /I option is correct and that the hardware is functioning. Otherwise, when an application attempts to use the hardware (i.e. an RTMIDI application that wants to record MIDI), it will receive an error message.

This parameter can be set with the I/O and IRQ boot-time checking option.

NOTIMER0 - Do not use TIMER0

Do not use TIMER0 even it is available.

This parameter can be set with the MMPM/2 TIMER0 resolution option.

10BITS - Use 10-bit address width with RM

Always register each I/O address as having only 10 significant bits. If this option is selected, no I/O address can be greater than 0x3FF. See the section titled Resource Manager I/O address width for a detailed explanation.

This parameter can be set with the Resource Manager I/O address width option.

16BITS - Use 16-bit address width with RM

Always register each I/O address as having the full 16 significant bits. See the section titled Resource Manager I/O address width for a detailed explanation.

This parameter can be set with the Resource Manager I/O address width option.

ONLYONE - Locate only one MPU-401 device

Ignored unless I/O port autodetection is used. When specified, the autodetection routine stops after finding the 1st MPU-401 device.

This parameter can be set with the Number of devices to autodetect option.

AUDIOVDD - Enable DOS sharing

When DOS sharing is enabled, DOS applications which use the MPU-401 hardware will not interfere with OS/2 MIDI applications, and vice versa. DOS sharing support is provided by the virtual device driver, VMPU401.SYS.

If an OS/2 application is using the MIDI hardware (e.g. playing a MIDI file), and a DOS application is started which attempts to use the same hardware (e.g. a DOS or Windows MIDI sequencer), OS/2 will display a warning message giving you the option to terminate the DOS application or hide the hardware from the DOS application.

If a DOS application is using the MIDI hardware, and an OS/2 application is started which also tries the use the same hardware, the OS/2 application will receive an error message that the hardware is in use.

When /O:AUDIOVDD is specified, only those resources which are marked as "exclusive" (with the Resource Manager) are actually protected in this manner. Also, the support for DOS sharing is currently rather primitive. First, only one IRQ is protected - if one instance of the MPU-401 driver controls multiple MPU-401 devices, only the IRQ for the first device is protected. Second, the protection is global for all devices per driver - if one instance of the MPU-401 driver controls multiple MPU-401 devices, then all resources across all devices are protected globally, which means you cannot use an OS/2 MIDI application with one MPU-401 device and a DOS MIDI application with another.

All of these limitations are expected to be removed in the next version of the driver.

Using the MPU-401 driver with other audio device drivers

The MPU-401 driver has been designed to allow co-exist with other audio drivers. However, when using the MPU-401 driver in this way, you will effictively have two device drivers that do not communicate with each other sharing the same hardware. This combination can cause odd, unpredicable behavior that can vary from driver to driver and even from version to version.

The other audio device driver, hereby known as the main driver, typically controls an entire adapter, and the MPU-401 driver only talks to the MPU-401 hardware on that adapter. In some cases, the main driver also talks to the MPU-401 hardware.

In particular, there are two problems that occur most frequently:

  1. The main driver controls the audio mixer, and can mute the wavetable synthesizer on the adapter. The audio mixer controls the volume levels of each of the devices, such as the wavetable synthesizer, on the audio adapter. The MPU-401 device on an audio adapter typically controls the wavetable synthesizer. The MPU-401 driver can only control the MPU-401 device on the adapter, and the audio mixer cannot be controlled by the MPU-401 device.
  2. The main driver can reset the MPU-401 device for an unrelated reason (such as when initializing the wave audio device), and thus preventing simultaneous use of the wave audio device and the MPU-401 device (i.e. you will not be able to get digital audio and MIDI at the same time).

The default options for the MPU-401 driver will usually prevent the MPU-401 driver from co-existing with other drivers. This is because the MPU-401 driver registers its resource with Resource Manager in "exclusive" mode, and this usually conflicts with the main driver. If this is the case, three things must be done:

  1. Determine whether the conflict is with the I/O ports, the IRQ, or both.
  2. Determine how the main driver registers the resource with RM: shared, multiplexed, or exclusive.
  3. Use the chart below to determine how to set the MPU-401 driver
Main driver is set to: 	Set MPU-401 driver to:
Shared 	Shared
Multiplexed 	Multiplexed
Exclusive 	None

For example, if the main driver registers its I/O ports in exclusive mode and its IRQs in multiplexed mode (a common configuration), the MPU-401 driver should set Resource Manager I/O Usage to "None" and Resource Manager IRQ Usage to "Multiplexed".

Creative Labs SoundBlaster Pro (TM) and compatibles

If your soundcard is a SoundBlaster Pro or 100% compatible, then it is incompatible with the MPU-401 driver. The SB Pro does not contain any MPU-401 hardware, and so there is nothing for the MPU-401 driver to talk to. The SB Pro is a very old card that lacks many features of modern sound cards. For instance, it also does not support 16-bit audio.

Note that many modern sound cards include SB Pro compatibility, but can also do much more. Many of these cards also include real MPU-401 hardware, so the MPU-401 driver will work with these cards. But if your sound card supports only the SB Pro standard, then it will not work with the MPU-401 driver.

Creative Labs Soundblater 16 PnP ISA card

Reports of success with this card vary. Generally, IRQ-based MIDI recording will not work, but IRQ-less recording does work for some people.

One person uses the SB16D2.SYS driver dated Jan 1 1997 (69,670 bytes). The command-line options used are "P1:330 /I1:0 /O:NORMIO", but MIDI recording does not work with this card.

Terratec Maestro-32 with Yamaha DB50XG daughter board

One person is using this board with the Crystal Semiconductor 1.75 reference drivers and these parameters:

/P1:330 /I1:7 /O:LONGNAME /O:NOCHECKIRQ /O:16BITS $

It is unknown why the /O:NOCHECKIRQ parameter is required. The system is an IBM Server 330 with known BIOS problems, so that may be the cause. Hardware detection (Warp 4) needs to be disabled for the driver to find the board. Other than that, all features appear to work.

Sound cards using the ESS 1869 chip

The ESS 1869 hardware is not capable of MIDI input, so MIDI recording will not work with any sound card that uses this chip.

Therefore, do not specify an IRQ. The driver will attempt to locate an IRQ, and when it can't find one, it will simply ignore it. Do not use IRQ-less recording, as this will not work.

Creative Labs SoundBlaster AWE 32

The AWE 32 has both an internal wavetable synthizer (for MIDI music) and MPU-401 hardware compatibility. However, the two are not connected. The MPU-401 hardware can communicate only with the MIDI connector on the back of the card, so the MPU-401 driver can only work with external MIDI devices, not the internal synthesizer.

At this time, there are no confirmable reports as to how to get the MPU-401 driver working with the AWE 32.

PCI audio devices

To our knowledge, there are no PCI audio devices which are compatible with the MPU-401 driver.

Win-OS/2 support

You should be able to install the Windows MPU-401 driver without any difficulty. Note that the Windows MPU-401 driver only supports the following I/O ports

  • 300
  • 320
  • 330
  • 332
  • 334
  • 336

and IRQs

  • 3
  • 4
  • 5
  • 6
  • 7
  • 9 (same as 2)

You must make sure that your MPU-401 hardware is configured for these settings before you try to install the Windows MPU-401 driver.

Follow these steps to install the Windows MPU-401 driver:

  1. Start Win-OS/2, either Full Screen Win fs.png or Window Win win.gif
  2. In the Program Manager, open the "WIN-OS/2 Main" group. From there, launch the Control Panel CPanel.png
  3. Launch the Drivers control panel Wdrivers.png
  4. A dialog box appears, with a list titled "Installed Drivers". If there is an entry titled "Roland MPU-401", then select it, click on the button "Setup", and jump to step number 7.
  5. Click on the button "Add"
  6. In the list titled "List of Drivers", select "Roland MPU-401" and click on "OK". If it asks whether you want to use the current driver or a new driver, click on "Current".
  7. A dialog box labelled "MPU-401 Compatible Setup" appears. Select the Port and Interrupt (IRQ) that corresponds to the MPU-401 hardware, and click on "OK".
  8. A dialog box will appear asking if you want to restart Win-OS/2. Click on the button "Restart Now". Win-OS/2 will terminate.
  9. Launch Win-OS/2 again
  10. Launch the Control Panel again, and then launch the MIDI Mapper. Mapper.gif
  11. In the area labelled "Name", select "MPU-401" if it isn't already selected. To see all the selections, click on the small down arrow next to the "Help" button.
  12. Click on the button "Close". Then close the Control Panel window.

To play a MIDI file in Windows, do the following:

  1. In the Win-OS/2 Program Manager, inside the "Win-OS/2 Accessories" group, is an icon for the "Media Player" Mplayer.gif . Launch it.
  2. Select the menu item Device->MIDI Sequencer.
  3. Select a MIDI file to play.
  4. Click on the play button.