sizzlinbeef wrote on 2026-05-31, 17:17:

Yes, jumpering JV6 gets the correct 2.5v. […]
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Chkcpu wrote on 2026-05-30, 19:51:

First close only JV6 and check if you indeed get 2.5V Vcore. Then also close JV7 and check the voltage. Depending on how the JV6 […]
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First close only JV6 and check if you indeed get 2.5V Vcore.
Then also close JV7 and check the voltage. Depending on how the JV6/JV7/JV8 resistor network is connected, you will see the Vcore either go down or go up.
Repeat the experiment with all other JV6/JV7/JV8 combinations.

If the voltage goes up with more than one JV6/7/8 jumper closed, a final test with all three JV6/7/8 jumpers open may reveal the lower Vcore you want to find.

I hope this procedure is clear and I’m curious what you will find.

Happy testing,
Jan

Yes, jumpering JV6 gets the correct 2.5v.

6-7 closed 1.93v
6-7-8 closed 1.73v
7-8 closed 2.04v
6-8 closed 1.95v

Unfortunately I can't confirm any of these result in a working system. I tried booting this board before testing. Using default settings for a pentium MMX (I tried a 166, 200, 233), can't get the thing to post. No video output. Tried different VGA, RAM, deoxit on all slots, alcohol clean, etc. I think time has taken it's toll on something on the board. It may be related to getting 3.6v on the VIO transistor when it should be 3.3v with JV1 and 2 open and JV3 set to 2-3. It has been probably a decade since I last tried booting it, so not surprising.

Thanks for reporting your test values.
So a 2.2V setting was not among them, but you found a nice 2.04V setting for a K6-2+! 😀

I’m sorry to hear the board won’t boot. The CMOS backup battery inside the DALLAS or BENCHMARQ RTC chip is probably dead. This sometimes causes a board to stall early during the Power-On-Self-Test.
Do you have a POST analyzer card to see where the boot process hangs?

Cheers, Jan

Ciao Jan,
I wanted to let you know that I downloaded the BIOS version 2.0 that you provided me, but currently I can't try it, because I'm away for work, but I have the ZIDA 5SVA-E motherboard on the bench, so as soon as I have the opportunity to dedicate a few minutes to it, I'll upgrade the BIOS, then I could try other CPUs, currently there is a Cyrix MII 300 (233 MHz), but if I remember correctly, it is possible to select lower voltages, for AMD K6 CPUs from 2.2V for example, maybe it could be possible to get up to 2.0V, but I don't think you can select lower voltages, this I think is possible only after modifying the motherboard, which I wouldn't do anyway, not having this need.
Greetings 🖖

PC@LIVE wrote on 2026-06-01, 09:08:

Ciao Jan,
I wanted to let you know that I downloaded the BIOS version 2.0 that you provided me, but currently I can't try it, because I'm away for work, but I have the ZIDA 5SVA-E motherboard on the bench, so as soon as I have the opportunity to dedicate a few minutes to it, I'll upgrade the BIOS, then I could try other CPUs, currently there is a Cyrix MII 300 (233 MHz), but if I remember correctly, it is possible to select lower voltages, for AMD K6 CPUs from 2.2V for example, maybe it could be possible to get up to 2.0V, but I don't think you can select lower voltages, this I think is possible only after modifying the motherboard, which I wouldn't do anyway, not having this need.
Greetings 🖖

Ciao Elio,

Thank you for going to test the patched Zida 5SVA(-E) BIOS.
If you can test it with a K6-2+ or K6-III+ that would be great.
But there is no hurry, so take your time.

Earlier you found that this board uses a HIP6008CB controller, so by using the four JP9 jumpers, the Vcore can be set from 2.0V to 3.5V in 0.1V increments.

Pulling all JP9 jumpers OFF will generate 2.0V.
Placing jumper JP9/1-2 will add 0.1V
Placing jumper JP9/3-4 will add 0.2V
Placing jumper JP9/5-6 will add 0.4V
Placing jumper JP9/7-8 will add 0.8V

Using any combination of these 4 jumpers, all 16 Vcore settings from 2.0V to 3.5V can be made.
And of course the JP8 jumpers block must be at position 1-2 for dual-voltage CPUs.

Greetings, Jan

Chkcpu wrote on 2026-05-31, 19:47:

I’m sorry to hear the board won’t boot. The CMOS backup battery inside the DALLAS or BENCHMARQ RTC chip is probably dead. This sometimes causes a board to stall early during the Power-On-Self-Test.
Do you have a POST analyzer card to see where the boot process hangs?

Cheers, Jan

Interesting. I've had many dead Dallas rtcs, this particular one is an ODIN clone, but haven't heard of a dead one preventing a computer from posting. They've always just annoyingly lost the BIOS settings on reboot. I'll battery mod this one and see if that changes anything. I do not have a post analyzer board.

Mike_ wrote on 2026-05-31, 07:18:

Actually I also noticed that hidden setting after I had posted the ROM files, but unfortunately it didn't help. […]
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Actually I also noticed that hidden setting after I had posted the ROM files, but unfortunately it didn't help.

But I got an idea what might be causing this on hardware side. Near south bridge there are two IC footprints, but there are only two resistor nets there instead.

The attachment south_bridge.jpg is no longer available

Those resistor nets are between ISA slot and south bridge on address lines 0-15, but 470Ω is awfully lot of series resistance even for a slow bus like ISA. On 686B south bridge those lines are multiplexed with secondary IDE's data lines, so maybe the point is to prevent ISA bus messing with whatever is happening on secondary IDE. Looking at pictures of GA-7ZX, which has ISA slot as an option, there are two TI's "F245" chips.

The attachment ga-7zx.jpg is no longer available

https://theretroweb.com/motherboards/s/gigabyte-ga-7zx-1.x

I suppose it could be this? Locations of GND and Vcc pins match, and OE on both sockets is low when board is running, ie. it's enabled. I guess Gigabyte figured out that a cheap resistor net would suffice for reading from a slow BIOS chip during startup, and there's no need to have an actual IC there. 😁

https://www.ti.com/lit/ds/symlink/sn54f245.pdf

Unfortunately soldering in these chips didn't help, either. 🙁 So there must be something else going on. Is there some DOS utility that could be used to dump PCI configuration space? It could be that some PCI-ISA bridge settings are out of whack... for example, I wonder if this part from datasheet means that by default 16bit ISA bus is turned off or something?

POST diagnostics card also arrived, and it seems to work correctly on the ISA slot. I also tried Tie Fighter a bit more, and it appears that some sounds in the intro, such as the spacecraft flying around, sound OK but speech is garbled. It's as if speech would be way slower than it should be.

Mike_ wrote on 2026-06-04, 15:32:

Unfortunately soldering in these chips didn't help, either. 🙁 So there must be something else going on. Is there some DOS utility that could be used to dump PCI configuration space? It could be that some PCI-ISA bridge settings are out of whack...

Hi Mike_,

Yes there is a DOS tool to dump the configuration space of all PCI devices.
It’s called PCISNIF and the program creates a detailed log-file when hitting the F2-key.

You can download this PCI Bus sniffer DOS tool from an earlier reply in this thread:
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb

Cheers, Jan

Chkcpu wrote on 2026-06-04, 19:03:

Hi Mike_, […]
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Hi Mike_,

Yes there is a DOS tool to dump the configuration space of all PCI devices.
It’s called PCISNIF and the program creates a detailed log-file when hitting the F2-key.

You can download this PCI Bus sniffer DOS tool from an earlier reply in this thread:
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb

Cheers, Jan

Hello, Jan. I just tried another tool called TweakPCI and I read registers 0x40 and 0x42. It appears that "Extended ISA bus ready" and "MCS16# Output" are disabled... I wonder if this could cause problems with 16bit ISA cards?

I'll try that PCI bus sniffer tomorrow.

1C:\TEMP>tweakpci -b 0686 1106 b40
2TweakPCI - PCI configuration tool v1.0 by TimmermanV
3Tweaking device: DeviceId 0x0686, VendorId 0x1106, DeviceIdx 0x0
4Device found: BusNr 0x00, DeviceNr 0x07, FunctionNr 0x0
5
6Register 0x40 (8-bit)
7Cur value: 0000_1000
8
9C:\TEMP>tweakpci -b 0686 1106 b42
10TweakPCI - PCI configuration tool v1.0 by TimmermanV
11Tweaking device: DeviceId 0x0686, VendorId 0x1106, DeviceIdx 0x0
12Device found: BusNr 0x00, DeviceNr 0x07, FunctionNr 0x0
13
14Register 0x42 (8-bit)
15Cur value: 0000_0000

Use wpcredit from 9x.
It should have an appropriate pcr file.

Here. This might help.
It's an automatically converted K7m pcb and rudimentary schematic.

Looks like Asus didn't make a 686b board with isa so 686a will have to do.

I assume you populated the unpopulated resistors here, right...?

In particular DRQ/DACK5 stand out to me.

myne wrote on 2026-06-05, 06:05:

I assume you populated the unpopulated resistors here, right...?

Here's a picture before I installed the ISA slot. Most of the passive components are already populated, the empty resistor net was for address lines 20-23 but AWE64 doesn't use those anyways. The resistor for DACK5 is missing here as well (I noticed that it was missing and I populated it).

Quickly looking at it, it appears that at least most of the components in your picture are already populated, but I'll check it out later today.

Drq/dack5 was what stood out to me.

Everyone a hundred years old memorised irq 5 dma 5,7 220 330

myne wrote on 2026-06-05, 06:20:

Drq/dack5 was what stood out to me.

Everyone a hundred years old memorised irq 5 dma 5/7 220 330

Yes, I noticed that earlier and added a resistor there.

What's the 4th from the right missing resistor go to once it goes through at "D1" ?

myne wrote on 2026-06-05, 06:25:

What's the 4th from the right missing resistor go to once it goes through at "D1" ?

That missing resistor is shorted out by the trace. I don't understand why there are pads to begin with. But it goes to S_IRQ connector near BIOS chip and also some test point near south bridge IIRC. But Creative's diagnose.exe says DMA5 is working after I installed the resistor, so I think that's probably fine now.

https://theretroweb.com/motherboard/image/7zx … d2076084371.jpg

It would seem that something somewhere isn't going where it should.
The good news is you can reasonably make some assumptions and cut down your test/search "area"

https://dosdays.co.uk/topics/images/sb_ct3600.jpg
https://dosdays.co.uk/topics/images/ct3600_6.jpg

It's not unreasonable to assume that the missing pins on this random card are not relevant to yours.
Test/trace the remainders - including the 8 bit part.

myne wrote on 2026-06-05, 08:40:

It would seem that something somewhere isn't going where it should. The good news is you can reasonably make some assumptions a […]
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It would seem that something somewhere isn't going where it should.
The good news is you can reasonably make some assumptions and cut down your test/search "area"

https://dosdays.co.uk/topics/images/sb_ct3600.jpg
https://dosdays.co.uk/topics/images/ct3600_6.jpg

It's not unreasonable to assume that the missing pins on this random card are not relevant to yours.
Test/trace the remainders - including the 8 bit part.

POST diagnostics card seems to work fine, so probably at least pins needed for 8bit writes work. This should narrow it down further.

Looks like there's no 14MHz clock on OSC pin, and AWE64 does seem to have contact on that pin, unlike AWE32... and unlike AWE32, it doesn't seem to have any crystals on board either. Maybe this could be an issue?

EDIT: And yes, there seems to be another missing resistor...

EDIT2: And I got it working finally. 😁

yay
So... I was accidentally on the right track when I asked about the xtal 🤣

Now you have to write a how to guide for the next guy in 6 years who googles "how do I...?"