Chupperson wrote:

Hi,
I'm trying to locate the proper jumper settings for my particular motherboard revision and having a heck of a time. It's an Opti 495SLC 3/486 board marked Rev. B and none of the documentation I can find online has the jumpers in the right place to match my board.

The BIOS string is 40-040B-001117-00101111-080893-OP495SLC-F.

http://www.kva.kursk.ru/bios1/numbersami.shtml

That 1117 indicates it's an A-Trend board.

Googling the OP495SLC-F dug this up:
http://www.elhvb.com/webhq/models/486vlb2/opti495slc.htm

That looks like your board:

If so, the .zip file on that web site contains some .pcx image files (retro indeed 😜 ) with the relevant settings.

I'm trying to put a 486DX2-66 in place of the TI/Cyrix 486DLC and 487 that are currently installed. I just don't want to break anything.
The clock is currently set at 33MHz despite the fact that my 486DLC seems to be a 40MHz chip.

Possibly it's misconfigured (maybe the DLC was an upgrade from a 33MHz part and the previous owner messed up the jumper settings), or perhaps the VLB cards didn't like a 40MHz bus speed and needed 33MHz to be stable.

In any event, this is an interesting board, that's a socket that can accept either 386 or 486 CPUs (the 486DLC is technically a very advanced 386, not a 486 clone). Most important thing to get right is the orientation of the CPU. There's no keying on the socket so you can physically put it in any way. Only one out of four will work and there's a good chance the other three will let out the magic smoke...

Edit: nope, now I look better at the picture it's very similar, but not the same, and the jumpers look different. Sorry 😢

Chupperson wrote:

Hi, I'm trying to locate the proper jumper settings for my particular motherboard revision and having a heck of a time. It's an […]
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Hi,
I'm trying to locate the proper jumper settings for my particular motherboard revision and having a heck of a time. It's an Opti 495SLC 3/486 board marked Rev. B and none of the documentation I can find online has the jumpers in the right place to match my board.

The BIOS string is 40-040B-001117-00101111-080893-OP495SLC-F.

I'm trying to put a 486DX2-66 in place of the TI/Cyrix 486DLC and 487 that are currently installed. I just don't want to break anything.
The clock is currently set at 33MHz despite the fact that my 486DLC seems to be a 40MHz chip.

Thanks for any and all help.

Post a full picture of your motherboard - just so that we can be sure (I noticed a small difference of your board in the lower left corner, compared to the one that dionb posted.
However, the one that dionb posted was also manufactured by DataExpert (model EXP3406).

Thanks.
I found those PCX files as well. That board is nearly the same as mine except the jumpers are all in different places.
I didn't want to take the board completely out of the case unless I need to, so let me know if seeing the other part is of any use.

I think I found it!
It's "unidentified" according to this site.
http://stason.org/TULARC/pc/motherboards/U/UN … -BUS-3-486.html

The amount of slots is correct and the jumper numbers all seem to correspond...

Yes, I think you've got it - here's a better link: http://arvutimuuseum.ee/th99/m/U-Z/32085.htm
See if you can get a VESA Local Bus graphics card to work with your Cyrix CPU.

I sent you a PM as well.

I actually have a VLB Diamond Speedstar Pro in it right now and it works quite nicely.

Speaking of VLB cards, if I get an EIDE interface card, can I overcome the 504MB drive limit? How would I find out for this board?

You have to fine the VLB I/O controller card with it's own BIOS. Or go the route of DDO, more here:

504 MB / 1024 cylinder limit 486 BIOS

I just found that I had a copy of Conner Disk Manager (a version of the OnTrack DDO) that can detect all 16GB of my CF card, but it was only able to create 2 2GB partitions which are only readable on the 486. Judging from Phil's video about OnTrack, maybe later versions don't have that issue or maybe I'm leaving out an important step.
What DDO do you recommend?

Doesn't FAT16 in DOS have a partition size limit of 2 GB? I think NT4 can get away with 4 GB by using larger cluster sizes. You will need to use FAT32 if you need larger partitions.

I should also say that I only have a 16GB card because that's the smallest I could find locally.

It is indeed limited to 2GB partitions. I'm less concerned for the moment with the size of the partitions and more with the ability to copy files using a CF card reader while using more than 504MB of the card. I should be able to get at least 3 partitions on that card along with my HDD, I think. I don't know if the limit is 4 total partitions per computer or per drive under DOS.
I know it's possible to use Win98 DOS and have FAT32 support but that seems kind of silly. I mainly want to run my 486 with the HDD for OS use and the CF card for games. I haven't been able to tell if using one of the newer Ontrack tools will allow me to boot from my HDD and keep regular DOS partitions on the CF card.

I have a 386 board with a 486SXL (like the DLC, but with 8 kb L1 cache). I transfer files via ethernet in Windows 3.11. I don't mess with IDE unless it is on a test system, in which case, I limit the HDD size to around 500 MB. On my cased system, I use SCSI with its own BIOS and don't worry about the motherboard's BIOS IDE size restriction, nor do I have to deal with tools like Ontrack to translate the HDD size. I use 2 GB SCSI partitions without an issue. The Adaptec 1540 series is a popular ISA SCSI card with DMA, the 1520 series for without DMA.

Isn't the limit 4 primary partitions? I'm not sure what the limit is for logical drives in an extended partition. I tend not to use more than 4 partitions, even today.

That's definitely something to look into.
For ethernet, is it harder than having Windows install the drivers and connecting it to a router? I put an ethernet card in this machine with exactly that intention but I haven't done anything with it yet.

There exists a Microsoft-provided TCP/IP executable installer you run for Windows 3.11. You also need to install the Windows 3.x drivers for the ethernet card, which are provided by the manufacturer. Then you use Windows Explorer in Windows 3.11, or in your more modern Windows OS to connect to Win3.11. For Win3.11 to view other computers, you just need to 'Map Network Drive' from within Win3.11-Windows Explorer.

feipoa wrote:

Isn't the limit 4 primary partitions? I'm not sure what the limit is for logical drives in an extended partition. I tend not to use more than 4 partitions, even today.

As Dos only supports 1 primary partition per physical disk a normal IDE system would be limited to 4 (or 3 with a CD-Drive) SCSI would be how ever many drives you have.
Logical drives are limited to available drive letters.

I had a Dos 6 PC with 3 8GB drives partitioned in 2GB chunks, that's c:\ thought to n:\
Was total overkill and finding anything was a pain, but I can cross it off my list of things to do!

1 primary + up to 3 logical in extended partiton per HDD. CD units don't count.

Quick question, when you overclock the ISA bus on a 386-DX40, how come benchmark scores dont increase when using an ISA video card?

I've seen benchmarks scores with 386-DX40/VLB combos scoring higher FPS in 3dbench or doom yet overclocking the ISA bus doesnt increase?

Makes no sense to me.

dirkmirk wrote:

Quick question, when you overclock the ISA bus on a 386-DX40, how come benchmark scores dont increase when using an ISA video card?

I've seen benchmarks scores with 386-DX40/VLB combos scoring higher FPS in 3dbench or doom yet overclocking the ISA bus doesnt increase?

Makes no sense to me.

The cards generally have their own clock generator, so overclocking the bus doesn't affect the speed the video chip is running at, all it does is increase the bandwidth to/from the card. You'd only see an increase in performance if that bandwidth was the bottleneck.

chinny22 wrote:

feipoa wrote:

Isn't the limit 4 primary partitions? I'm not sure what the limit is for logical drives in an extended partition. I tend not to use more than 4 partitions, even today.

As Dos only supports 1 primary partition per physical disk a normal IDE system would be limited to 4...

Thanks. I must have been thinking about NT4, which I used for a long time, a lot longer than I used DOS for.

So, I have my network card installed, but I get messages saying the network has responded incorrectly or that the lobe test failed. I'm assuming it doesn't know how to talk to my router, but none of the speed options, etc. seem to be doing any good.

As for drives, I have a VLB IDE card on the way which will at least allow me to add a CD drive in addition to my HDD and CF card for now. I don't have any SCSI hard drives so that's a project for later.
If I get a SCSI controller, does it just operate alongside the IDE controller, still giving me floppy access?

I might try to kill two birds with one stone and get a different network card with a ROM socket and burn the universal BIOS for large drive access.