IBM M-Audio Capture & Playback Adapter/A (M-ACPA) @6E6C

Audio Capture & Playback Adapter Diagnostics (and ADF!) Version 1.01 - 720K raw disk image / ZIP
General Info (Louis Ohland) / Mirror
Install Under Win95 (Peter Wendt)
SoundBlaster Support?
Audio Muting Implementation (uses an honest to goodness relay!)
Results Under Win95
Old (Rev A) Card
New (Rev C) Ultimedia Card
Audacity Software

Revision A - Old, Long Card
IBM M-ACPA/A Adapter

Y2 - 40MHz (DSP clock?)
U63 - Texas Instruments TMS320C25FNL DSP
U61, 64 - Cypress CG7C185-35VC
Y1 - 22.5792MHz (probably for CS5126 external clock -- see datasheet)
U20 - Crystal CS5126 (16 bit stereo A/D converter, datasheet here)
Blue - Takamisawa A5W-K 5VDC 1A/30VDC DPDT relay (for muting function)

Revision C Ultimedia ACPA - Newest, Short Card
Ultimedia M-ACPA Revision C

U2, 3 - National Semiconductor LM386
U12 - Crystal CS5126-JL (16 bit stereo A/D converter, datasheet here)
U13 - Texas Instruments CF62357APQ (possible MCA bus interface)
U16 - Texas Instruments TMS320C25FNL DSP
U17 - Cypress CY7C185-20VC
U18 - Cypress CY7C185-20VC
OSC1 - 22.5792 & 40.0 MHz (CS5126 clock and DSP clock - all in one package!)
Q1 - Takamisawa A5WK (in a white casing, for audio muting)
T1-T7 - TDK ZJYS-2

J2 - CD Audio Connector
P4 - Ultimedia Connector (pin 1 as marked)
LI - Line In
MI - Microphone Input
LO - Line Output
SO - Amplified Speaker Output

Audio Mute

In regards to the muting function, Peter Wendt said:

I have the M-ACPA in various machines - one of them is a Server 85 (33MHz
planar) with Kingston Turbochip 586-133 installed. Works nice.
- is not Soundblaster compatible and will never be
- volume control and mixer don't work (consequently - requires SB-comp. card)
- the audio-mute is a relay, which causes a loud clicking noise in the output
- the .MID-files sound a bit odd since the instrument tables differ
Apart from that it works pretty good and the audio quality is a lot better
compared to ISA-sound card. The digitizer part (analog in) is 10X-better than
on any other ISA-card due to the better signal / noise ratio of the MCA. I use
one ACPA to digitize my old analog records.

Sound Blaster Support?

Yes, in at least some sense of the term. Christian Holzapfel turned on the unobtainium mill and cranked this out:

Yes, it is true!
While sorting my floppy disks I found one named "Virtual device driver
vor M-Audio Capture and playback Adapter", which came with my 9577-STG
a few years ago.
However, I uploaded the content to
so everyone can experience this.

These are the magic files:

19.10.1992  14:15 79.808 ACPA.DLL
26.10.1992  14:31 65.747 ACPAD2.SYS
19.11.1992  13:15 67.636 ACPADD2.SYS
01.09.1992  14:06 112.468 IBMMME.DRV
23.09.1992  12:00 14.957 IBMMPC.DSP
12.01.1994  15:38 1.062 MAUDIO.TXT
12.11.1992  11:31 799 MINIDD.SYS
24.11.1992  09:49 2.243 README.DOS
24.11.1992  15:17 1.865 README.OS2
24.11.1992  09:49 3.003 README.WIN
19.11.1992  10:01 91.273 SVAUDIO.386
23.11.1992  13:11 28.921 SVAUDIO.EXE
23.11.1992  13:22 18.432 SVAUDIO.SYS
20.08.1992  10:02 3.584 VAUDIO.SYS
23.11.1992  14:44 277 WININST.BAT

It needs to be installed manually, just read the appropriate file, "README.WIN" in most cases; WININST.BAT only does half of the job, so don't care about it. The emulation only works within a Windows DOS session, so the DOS driver seems useless to me. It is designed for Windows 3.1, but it also works under Windows 98 SE,I tested them both successfully. There mustn't be any other MACPA driver installed, not even the great one with the .inf from Peter. However, after you installed this one, sound works great within Windows too, although you don't see a device in the device manager.

There are not less than 4 readme files in the package, and useful information is spread all over:

"The VDD will allow you to run most SoundBlaster and MPU-401/MT32 or LAPC applications within a Windows DOS session.  Do NOT run the SVAUDIO.EXE. The VDD will attempt to map the sounds requested by the application to the nearest M-ACPA sound.  In most cases this is quite acceptable, but in any case it will sound different."


"If you turn music on for SoundBlaster support and specify port 240, music comes out great."


"(3) The M-ACPA must be set to Interrupt 5 for the SoundBlaster  emulation to have any chance of working. Otherwise, it may lock up your machine."


So, if you configure your DOS sound application (a.k.a. "game") to Int 5, I/O 240, everything works fine. If you need to specify a DMA channel, well... I locked up my '95 on every try. The reasons for this are clear, the MACPA simply doesn't need/support a DMA channel.

I tried "DOOM" without SFX and "Skyroads" with SFX, they both work, and the music themes are recognizable, but still sound a bit strange. Why this is, I can't say.

One more thing I noticed, all the files on the disk are dated later than the ones on any MACPA option/driver package. If you run "Audiover.exe" from the M-ACPA Win driver Corrective Service disk, it tells you the installed driver only supports up to 22.050kHz, Mono, 8-bit. If this is true, I cannot say. It doesn't sound that bad, but this is just my perception.

It looks to be an unfinished, inofficial driver set, since I could not find any information about it anywhere.
Finally, the README.DOS says: "Error handling is not very robust at this time. Be prepared to reboot." :-)
I had no problems so far, however.

What you need is here. (converted from a RAR archive to a ZIP file...rar, rar, rar, rar, grumble, growl...) It should be said that this is beta quality software (if that much!) and it may do Bad Things to your system.

Windows 95 Experiences (set-up procedure here.)

The M-ACPA sounds pretty darn good when playing waveform audio.

The MIDI implementation doesn't sound at all good under Windows 95. It sounds much better under OS/2 Warp 4. Some notes seem to be over-emphasized and others you can barely hear. Some wave sounds come through a bit strangely and others play fine. I can't explain that. This might be compression related. As with Audiovation, using 16 bit programs is your best bet for proper sound playback. Most 32 bit programs won't even see that you have the ACPA installed. I didn't try recording from any source.

Warning: You get no volume control on the ACPA that I can see. It looks to me as though the outputs are "full on" under Windows 95. For your ears' sake, use earphones or speakers that have an inline volume control.

MP3 files played nicely on my 9585-0XF using an old 16-bit version of Fraunhofer's MP3 decoder software and a Kingston 133MHz TurboChip CPU upgrade. To multitask I had to turn down the decoding quality a bit. You'd be hard pressed to hear the difference from ordinary computer speakers though.

Audacity Software

Louis Ohland (keeper of the Ardent Tool) was looking for a way to rip audio from CDs using a PS/2. At some point in the discussion, the use of the open-source Audacity audio editing software came up. This didn't solve his problem, as Audacity doesn't do that.

However, I was still interested in having a general purpose audio editing solution that would work on a PS/2. Unfortunately, Audacity is said not to work on Windows 95 (and quite possibly NT).

My personal experiences differ with those of the Audacity developers. I don't think they tested for compatibility with Win95/NT. Not only does Audacity run just fine on Windows 95 (using IE 5.5 SP2 and the Windows Desktop Update, which I prefer), but it also works reasonably well during playback with the M-ACPA hardware. (That a Win32 application works at all with the M-ACPA is already quite amazing. Most Win32 programs do not work due to the Win16-only drivers for the M-ACPA and Audiovation sound cards.)

I haven't yet managed to get recording from a microphone to work. All I got when I tried was a very loud noise. Nor have I tried the line inputs.

I tried both the 1.2.4b and 1.3.0b versions. Both worked fine on a PS/2 9585-0XF with a 133MHz AMD 486 CPU, 64MB RAM and a 2 GB IBM SCSI hard drive. Audacity benefits from having access to a high color display, but if you have an XGA-2 display adapter and can get the vastly improved XGA-2 Win95/98 driver from MCABase, this won't be a problem.

If you want to rip audio from CDs using a PS/2, Audiograbber seems to work well.

If you want to burn CDs, you might also be interested in reading about my own CD burning on a PS/2 adventure.

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Copyright ©2005-2008 by William R. Walsh. All Rights Reserved. Permission is granted to reproduce this material in its original form, or to use it in other projects. However, you MUST provide credit for any of the text and outline that you use. There are to be no charges assessed for access to this information other than those required to cover connectivity, media or duplicating expenses.