VOGONS


First post, by TheMobRules

User metadata
Rank Oldbie
Rank
Oldbie

Hi

I have an old UNI-486WB VLB motherboard that I saved from being scrapped a while ago, and recently I've been tinkering with it to get it working with optimal settings. It has an Unichip U4800VLX chipset and 3 VLB slots. I'm having some trouble with the configuration as I only used a VLB motherboard for about a year during the early 90s so my memories about it are quite fuzzy. 🤣

1. First of all, there are a few jumpers for configuring the VL bus but I don't understand what the manual states about them:

For the "VL2" slot I can set JP74 & JP75 to position 1-2 for "Slave" configuration while setting them to 2-3 position results in "Master/Slave" configuration.
For the "VL3" slot it's the same stuff but with JP76 & JP77 instead.

The first slot (that I would guess would be "VL1") is not even mentioned in the manual (I suppose it was written for a 2 VLB slot revision of the same board). 😒

Now, I assume this is related to VL bus mastering, but what do these settings mean? The only VLB card I will be using is the VGA, what would be the appropriate settings in this case?

2. The second issue is related to the memory/cache settings in the BIOS. It is the typical AMIBIOS from the early 90s with funky default colors such as pink and light green 😁. The following settings are available:

DRAM Read/Write [0WS, 1WS or 2WS]
SRAM Read [0WS, 1WS or 2WS]
SRAM Burst [Enabled/Disabled]
SRAM Write [0WS, 1WS or 2WS]

Considering I have an Intel 486DX2-66, 256KB of 20ns cache SRAM and 16MB of 60ns FPM DRAM what would be the optimal settings in this case? It only seems to work fine with fairly conservative settings (with at least 1WS on each option), which means performance is not great. Would swapping the cache with 15ns chips would allow for tighter timings?

Also, I am used to configure cache timings on other 486 boards with settings like "2-1-2", what would be the equivalent in this case?

Thanks in advance for your help, I have scanned the manual and attached it in case it's useful. 😉

Attachments

  • Filename
    UNI-486WB.pdf
    File size
    4.74 MiB
    Downloads
    74 downloads
    File license
    Fair use/fair dealing exception

Reply 1 of 3, by NJRoadfan

User metadata
Rank Oldbie
Rank
Oldbie

VLB Video cards don't use bus mastering, so its a moot point. Can you post the BIOS string that shows on the lower left hand corner of the POST screen? I long suspect this is the motherboard that was in my first 486, but the only evidence I have to ID the board is a very fuzzy video of the machine running the post test.

Reply 2 of 3, by TheMobRules

User metadata
Rank Oldbie
Rank
Oldbie
NJRoadfan wrote:

VLB Video cards don't use bus mastering, so its a moot point. Can you post the BIOS string that shows on the lower left hand corner of the POST screen? I long suspect this is the motherboard that was in my first 486, but the only evidence I have to ID the board is a very fuzzy video of the machine running the post test.

The BIOS string is:

40-0200-001107-00101111-111192-U4800VLX-F

Here are some screenshots (POST screen, BIOS configuration):

8KB6GKKl.jpg

vc9gia5l.jpg