Testet my LAPC-I.
Unfortunatelly LA synthezis part of LAPC doesn't work on this system. Speaker minijack out and RCA outs silenced. But MPU-401 part of card works very well, like MPU-401AT and SCC-1 midi outs. And MT-32 hooked with mcb-1 box to LAPC sounds beautiful.

And more, tested LAPC on MVP3 / AMD K6-2+ 500 - all ok, card works just fine - midi port and internal outs too.

aleksej wrote:

Testet my LAPC-I.
Unfortunatelly LA synthezis part of LAPC doesn't work on this system. Speaker minijack out and RCA outs silenced. But MPU-401 part of card works very well, like MPU-401AT and SCC-1 midi outs. And MT-32 hooked with mcb-1 box to LAPC sounds beautiful.

And more, tested LAPC on MVP3 / AMD K6-2+ 500 - all ok, card works just fine - midi port and internal outs too.

Interesting. Thanks for taking the trouble to perform the tests. I'll note them down.

Did you check if the mobo (or PSU) deliver -5V to the isa slot ?

Did you check if the mobo (or PSU) deliver -5V to the isa slot ?

That is probably the reason, it is extremely unlikely that the MPU-401 interface portion of the card uses the -5v rail.

Maybe I'm wrong, but I'd say it's more likely that either his motherboard or LAPC is beginning to fail or it's a memory addressing issue.

Does the motherboard have settings for PCI and ISA bus timings? Alot of ISA sounds devices, especially old ones like your card, are very picky about timing. Make sure the PCI bus is at 33MHz and the ISA bus is running at 1/4 of that. (7.16Mhz or so) Also, look for settings labled (16 bit / 8bit , though it may not say this) I/O recovery time, which will have options of different numbers (2clks, 4clks, 8 clks, ect) and trying increasing those.

StickByDos & Great Hierophant, no, i didn't check this, but as i say before all MPU interfaces working very well here.
dh4rm4, LAPC functioning ok in another mobo.
Moogle!, i know all these options is useful in this case but unluckily none of them is present.

aleksej wrote:

StickByDos & Great Hierophant, no, i didn't check this, but as i say before all MPU interfaces working very well here.

The MPU portion of the LAPC-I doesn't use the -5V line, so the fact that it works isn't surprising. The LA-synth portion of the card does require -5v.

Grab a multimeter, and check that ISA slot. 😀

ISA in modern PCs can be quite problematic. There are alot of industrial mainboards available with ISA slot but mostly with just basic ISA features.

The main problems with modern PCs overall are:
- ISA has limited capabilities, f.e. no Busmastering support etc.
- modern PCIe cards do not necessarily support VBE 2.x anymore, just have a look at all the Geforce 6x00 threads.
- problems with ISA support of the BIOS, no working NMI (thats why AWEUTil does not work, probably MegaEM won't work either)
- [Q]EMM386 Manager unstable due to weird upper memory use of BIOS ROMs.
- Graphic card BIOS artificial speed limiting, f.e. most of the Geforce GTX do this. When I benched Duke3D f.e. it was fixed at 60fps at every resolution, while older cards worked unlimited. This might cause problems in some applications.
- limited FDC support. Some newer mainboards tend to be not able to boot from FDC anymore, while FDC access works under Win f.e.

Do modern PSUs provide any "-5v support", for want of a better phrase? I was thinking of using a modern PSU, with an ATX to AT converter, in order to power an older-style AT mobo.

Please note that I have used a modern PSU (Corsair HX520) in order to power an ATX mobo, which had 3 ISA slots, all filled with sound cards, without any noticeable problems...

Thanks for any advice. Best regards, Robert.

retro games 100 wrote:

Do modern PSUs provide any "-5v support", for want of a better phrase? I was thinking of using a modern PSU, with an ATX to AT converter, in order to power an older-style AT mobo.

Please note that I have used a modern PSU (Corsair HX520) in order to power an ATX mobo, which had 3 ISA slots, all filled with sound cards, without any noticeable problems...

Thanks for any advice. Best regards, Robert.

Most sound cards do not use -5v, which tended to be used more for old VGA cards and floppy disk controllers.

-5V support on modern PSUs is optional, so you need to check whether your particular PSU supports it. If it does, then the motherboard, if it uses ISA, should route it to the slot accordingly.

-5V can be made of -12V 😉

Hi guys.
I bought iBASE MB865-R motherboard and it seems that ISA DMA does not work properly. I only hear music/synthesis with my SBAWE32 PnP (CT3980 and 3990) but not the sound.
I almost tried everything like BIOS setting as memory hole, IRQ Resources / IRQ XX: Legacy ISA or PnP/PCI DMA Resources / DMA XX: Legacy ISA or PnP/PCI etc. Nothing helps.
I am going to buy iBASE MB820. Can you confirm for me if this MB really support ISA DMA?
There are another options. Have you ever heard about of these MOBOs? Does they support ISA DMA?
Axiomtek IMB-200
Itox/DFI G7S620-N-G
Etoptek ATX-E7

Thank you very much.

Anything with ITE IT8888x bridge will work good enough for ISA Sound applications, with DMA support and all that.
Anything with Winbond W83628x bridge will be a hit or a miss, as these chips don't offer DMA support as a regular feature. There are some motherboard who wire some support from the main chipset (Intel 845/65 only), and will work for ISA sound applications, you really can't tell it without testing them.

----
In the photos, i can see iBASE M8820 using Winbond W83628x bridge, so is pretty probable it will give the same results that the mobo you bought before, which uses the same chip 🙁.

Axiomtek IMB-200 >>> ITE Bridge, 85% chances it will work flawlessy, ITE chip onboard support for DMA, without requiring any special feature from the parent chipset. Advertised in its manual as suitable for retro gaming machine applications.

Itox/DFI G7S620-N-G >>> Winbond Bridge, will be a hit or a miss. 40% of chances it working for ISA sound applications.

Etoptek ATX-E7 >>> Obscure model, it is advertised as being compatible with ISA DMA, but isn't possible to check because isn't possible to tell which bridge chip it uses (is possible with intel i845 to wire ISA DMA support directly from the chipset, even with Winbond bridge, but isn't a standard feature). You need buy directly from them, as manual, drivers and bios files are password protected in the support site with a password that you only can get from them.

As how is seen in your options, i would put my bet in the Axiomtek IMB-200.

I have something to add. The fastest board that I've heard of someone getting ISA DMA working on is this:

http://www.portwell.com/products/detail.php?C … =RUBY-9719VG2AR

But there is some hacking required to get it working. You can read my thread the Retro Friendly Modern PC if you're interested:

The Retro-friendly Modern PC

AFAIK, PCI-to-ISA bridge chip such as the IT8888 will support DMA if the chipset is Intel 8xx, in particular, the 845/865/875. For newer chipsets, LPC-to-ISA bridge chips seem to be the only hope, but with some hacking required possibly.

I had another idea of using a machine with no ISA slots with a Costronic ISA bridge card with onboard IT8888 bridge chip, since there are some socket 775 boards with chipsets old enough to support ISA. I'm still researching these, but I'm will decide soon and start building someday soon.

Here's a page that has some useful information about chipsets that support ISA:
http://www.flaterco.com/kb/ISA_chipsets.html

popfuture wrote:

But there is some hacking required to get it working. You can read my thread the Retro Friendly Modern PC if you're interested:

The Retro-friendly Modern PC

Interesting information! Maybe Rabanik want to to try your utility fix before going and ditch the mobo that he just bought.

And are also interesting these kits from Costronic... But unfortunately are harder to get than industrial motherboards at fair price, and industrial mobos are already hard to get. Also there will be problems with case modding to accomodate the cards, and possibility also with power supply for them.

UPDATE: Interesting enough Costronic has public available datasheets for at least 1 Winbond ISA bridge family chipset type. Winbond claims being compatible with ISA DMA in these datasheets, so would be matter to understand how it works (not so easy i know), and make a patch to PCI configuration tables like with Finntek bridge, so we can enable DMA in these chips, and the boards using them can become useful for DOS sound applications.

Datasheet is available here.

In any case, no matter what isa bridge you choose, ite, wb, etc, you have to wire serirq, dmareq, dmagnt to bridge chip. Serirq is no problem, it always on multi io chip, but to track req/gnt pair is quite tricky if you don't have apparent mb service manual

If you want a small form factor with a peppier CPU but with full ISA support, try and find a D845GECL. There are some on still ebay.

The following photo is SIMILAR to my board. There are a number of listings on ebay of 845GL/854GL, etc. Some have winbond chips some do not. They all appear to be custom PCBs for various solutions so you compatibility might be a hit-or-miss.

I've owned two D845GECL motherboards and they are ideal for building an older retro computer where you want the extra processing power of a Pentium 4 but still have the use of your favorite ISA sound card.

These models are OEM industrial motherboard built by Intel for use by Siemens and are comprised of high quality parts. These particular boards I owned were used in France's "La Poste" postal service kiosks which eventually made their way to Hong Kong to be recycled.

I've done extensive testing with these and they're absolutely flawless as a retro board and is very compatible with QEMM for allocating lots of UMBs for TSR loading. There will be plenty of memory available for your favorite games.

This motherboard supports ISA Bus Mastering for DMA (Direct Memory Access); this means it is compatible with old DOS-era sound cards. I've tested it personally with a Gravis Ultrasound, SB16, AWE32, and AWE64.

Tested with Pentium 4 2.66Ghz and 3.06Ghz processors-- they work great!

One thing to note is that hard drive/SSD performance is very slow when running under protected mode DOS relative to real-mode which runs at a much higher speed. I could never figure out why or how to work around it.

On my P4 I used:

Scythe Shuriken Rev.B Quiet Low Profile CPU Cooler
http://www.newegg.com/Product/Product.aspx?It … N82E16835185097

For those looking to buy a P4 heatsink, you may be able to still find a Zalman CNPS7000B-Cu or variant. These are good coolers too:
http://www.newegg.com/Product/Product.aspx?It … N82E16835118119

Here is a photo of the Scythe:

I also own a Commell PMCA motherboard:
http://www.commell.com.tw/Product/SBC/PMCA.HTM

It's a nice board and works fine with a MIDI/synth ISA sound card but does not support DMA or bus mastering. One cool feature is that it has a PCIe video card slot. 🤣

Kahenraz wrote:

One thing to note is that hard drive/SSD performance is very slow when running under protected mode DOS relative to real-mode which runs at a much higher speed. I could never figure out why or how to work around it.

Have you tried something like UIDE (which replaces the BIOS's int13h services with its own UDMA-aware cached version)?