Try and deactivate all the IDE resources on the VLB controller. Could be some strange conflict going on.

Try swapping the cards around in the VLB slots. Another thing could be to browse Google Groups for help.

You are aware that 2x multiplier is remapped internally as 4x on the AMD 5x86 CPU? I take it you're running it as 33x3 atm, which gives a correct bus speed for VLB.

Pretty sure it's 33mhz X3.
Could be wrong, there's no real indication in BIOS or at start up what the current bus speed is.

The VL controller card is a UN1081 VL. nothing super fancy.
The CPU is Am5x86-P75 / AMD-X5-133. So, yeah, I think it's mapping x2 to x4.

could this be a write through/ write back problem?

DNSDies wrote:

could this be a write through/ write back problem?

I just noticed this is the SIS471 chipset. It has problems with controllers using bus mastering when WB is activated. That could be your issue. Try setting it to WriteThrough and see if that helps.

You should set the multiplier to 2x then, so you get full 133mhz 😀

the problem is finding out which jumpers control the multiplier.
The documentation for the MB only has a laundry list of settings for certain processors, not FSB/Multiplier settings.

Also, WT vs WB, will this affect performance much?
I actually like running windows 95 on this machine.

For 133mhz AMD see this post. Either Pentium Overdrive settings or AMD DX2/66:
https://groups.google.com/forum/#!search/4DMS … 2k/WA5tRIE-pw0J

New BIOS 1.05 here (support AMD cpu):
https://web.archive.org/web/19970429031842/ht … board/index.htm

Also, WT vs WB, will this affect performance much?

Very little, 5% tops.

Btw the way this board seem to be the eqviliant of JUMPER HELL

Also, I have an EPROM bios, but I have an EPROM eraser/writer, so this is very helpful!

Yup. Tons of jumpers. Very fun stuff.
I can't complain. I bought it as part of a complete 486 system for $2 from a junk sale.
Came with a nice horizontal AT case, 250W power supply (purrs like a kitten) and a 500MB hard drive.
Also had some kind of unidentifiable custom built controller card in a vesa slot, an Oak Technologies ISA video card, and an old Sound Blaster 16 (CT2770).

I'll take a picture of it when my CF to IDE converters come in and I get it filled up with stuff.
I'm going to try upgrading it to 1MB Cache and upgrade the Hercules Dynamite Pro VL to 2MB of DRAM too.

If you upgrade the bios just make sure to backup the one you already have. The best is probably to just burn the new BIOS to a new chip. Just to be safe 😀

Good thing I have a couple of AM27C512s on hand.
Should be more than enough to replace the BIOS chip.

You probably need 1mbit eprom, the 512's hold only 64kb of bios data.
Probably not enough for 486 boards.

actually 64kb is the standard for 486 boards...

The BIOS EPROM slot is only 28 pins, so it better be 64KB, or we're entering uncharted territory for custom EPROM chips.
I'm pretty sure it's 64kb, the updated EPROM BIOS linked earlier has a 64KB binary file in it.

Anyways, I tried setting the cache to Write Through, and it didn't help.
I'll update the BIOS today and see if that works. If not, I'll make sure the FSB is at 33Mhz and try again.

vetz wrote:

If you upgrade the bios just make sure to backup the one you already have. The best is probably to just burn the new BIOS to a new chip. Just to be safe 😀

Better is using a new eprom, and store the old as backup rom. (I put them in a little container) If iam few month further and the new bios is still work i put them in the eprom eraser.. So can use the chips for newer projects.
If you really want to be save.. Dump the bios to rom file.. So you can always write it back on an new eprom chip.

keropi wrote:

actually 64kb is the standard for 486 boards...

I can confirm 27C512 is standard on 486 boards.

On award BIOSes 1 long and 3 short beeps means there is a video card issue.

What is the bus speed at? I've heard of issues with more than one VESA card on higher bus speeds, like 40 and 50mhz.

I've tried it at both 25mhz and 33mhz, and there's no way to get the VLB Controller to work with the video card.

I think the card is busted.

You still have a chance that it is only an incompatibility /misjumpering issue.
I had met this phenomena many times before, sometimes permutating (swapping) the vesa cards helped - but even then, I had to enter the BIOS again to change some settings.
So, if you do not have dozens of VLB boards around for cross-cheking, I would suggest

1. clear CMOS entirely
2. enter BIOS, change setting from defaults to what you think to be the most compatible (loosen all timings, add delays to VESA clocks, disable ALL shadowing etc...)
3. when booting again with the multi I/O card inserted, immediately try to enter BIOS (kneel on the DEL key or whatever you need for that)

If VESA clocks / delays can be jumpered only, not BIOS-set, then you need expert eyes to guess which jumpers are responsible for that...

DNSDies wrote:

I've tried it at both 25mhz and 33mhz, and there's no way to get the VLB Controller to work with the video card.

I think the card is busted.

If you have an ISA VGA card laying around that would be perfect right now. Then you could boot the machine just with the VLB controller in the VLB slots.

The jumper settings in TH99 are not covering all supported processors. Though there are much more processor types included in the GOEFA/EFAUTIL configuration utility, it is not clearly stated which jumpers control relevant processor functions.

I finally found out the correct settings for the AMD 5x86 to run at 133 MHz in writeback mode.
Configure the jumpers according to the AMD 486DX4-100 3V SV8B table shown in EFAUTIL
To force 4x mode connect JP9 pin 2 with JP8 pin 3
To force writeback mode set JP46 to 2-3
Bios version 1.04 or greater is needed in order to get this working.

Make sure the VLB cards are correctly seated - it's very easy for part of the connector not to be fully inserted, and that'll produce the symptoms you're experiencing.

BastlerMike wrote:

The jumper settings in TH99 are not covering all supported processors. Though there are much more processor types included in th […]
Show full quote

The jumper settings in TH99 are not covering all supported processors. Though there are much more processor types included in the GOEFA/EFAUTIL configuration utility, it is not clearly stated which jumpers control relevant processor functions.

I finally found out the correct settings for the AMD 5x86 to run at 133 MHz in writeback mode.
Configure the jumpers according to the AMD 486DX4-100 3V SV8B table shown in EFAUTIL
To force 4x mode connect JP9 pin 2 with JP8 pin 3
To force writeback mode set JP46 to 2-3
Bios version 1.04 or greater is needed in order to get this working.

I know this thread is pretty old, but where can I get a copy of the util? I have this exact motherboard and would be interested in putting in this processor.