486DX/50 VLB Build \ VOGONS

486DX/50 VLB Build

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First post, by jasa1063

Posted on 2021-12-11, 04:25

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I have been wanting to put together a 486 VLB build for quite some time. I finally got around to getting everything together. I did not have any grand ambitions for this build, but wanted a stable running system that did not reach for stars performance wise. I settled on 486DX/50 as I already have 486 Pentium Overdrive 83 and AMD Am5X86/160 builds with PCI video cards. I also went for a modest VLB card in a Cirrus Logic CL-GD5426 1MB VLB video card. This card can run at 25/33/40/50 FSB speeds. I have a Diamond Viper VLB card, but it has an Oak OTI087 VGA chip with only 256K dedicate ram. My choice for the Cirrus Logic card is because the focus of this build is DOS and not Windows 3.x. The motherboard is a Biostar MB-1433/50UCV-e Rev 3 Socket 3 motherboard. Here are the system specs:

Intel 486DX/50 CPU
32MB 60ns 72-Pin SIMM
Biostar MB-1433/50UCV-e Socket 3 VLB motherboard
Cirrus Logic CL-GD5426 1MB VLB video card
Multi I/O ISA card with 1 IDE, 1 Floppy, 1 Serial, 1 Parallel port
3Com 3C509B 10Mb ISA Ethernet card
Sound Blaster 16 CT4170 sound card
Quantum Fireball 2.5GB IDE hard drive
1.44MB 3.5" floppy drive
XTIDE BIOS for large hard drive support
DOS 6.22 w/Windows 3.11

It took quite a bit of tweaking the video card to find the optimal performance settings. The video card actually makes the system run slower when clock at 50MHz. I ended up running at 33MHz as this motherboard can run the video card at a different speed and the CPU. I really like this case with the rocker switch on the front. It has a nice retro feel to it. Here are some pictures of the computer:

Last edited by jasa1063 on 2021-12-11, 05:57. Edited 2 times in total.

Reply 1 of 9, by jasa1063

Posted on 2021-12-11, 04:32

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Here are also a few benchmark results:

Reply 2 of 9, by jasa1063

Posted on 2021-12-11, 16:27

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Overclocking the GPU from 50MHz to 57MHz gives a nice speed boost in Windows 3.11. Here are the results:

Reply 3 of 9, by jasa1063

Posted on 2021-12-12, 16:42

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One last change. I swapped the 3.5" 1.44MB floppy drive for a combo 3.5" 1.44MB & 5.25" 1.2MB floppy drive. I think it matches the case much better.

Reply 4 of 9, by clueless1

Posted on 2021-12-12, 17:17

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Great looking system! What's on the monitor in the last screenshot? Looks like some sort of fractal map.

What are the games you're targeting for play on this system?

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 5 of 9, by jasa1063

Posted on 2021-12-12, 18:23

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clueless1 wrote on 2021-12-12, 17:17:

Great looking system! What's on the monitor in the last screenshot? Looks like some sort of fractal map.

What are the games you're targeting for play on this system?

The image on the monitor is a graphics demo called Bogussat, short for Bogus Satellite. It generates random images that look like satellite images. Attached is a copy of the program and the Turbo Pascal source code. This computer is targeted at DOS, so the games I am running include Wolf3D, Doom (running FastDoom), Sierra Games (Kings Quest, Police Quest & Space Quest), Monkey Island & Epic Pinball to name a few.

Reply 6 of 9, by chinny22

Posted on 2021-12-15, 14:57

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Why 50Mhz?
I get that you already have a POD 83 and 5x86 but would think a Dx2/66 rounds off the high end 486 line up nicely?
Sounds like you have a nice setup for some dos LAN gaming though!

Reply 7 of 9, by DaveJustDave

Posted on 2021-12-15, 17:06

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chinny22 wrote on 2021-12-15, 14:57:

Why 50Mhz?
I get that you already have a POD 83 and 5x86 but would think a Dx2/66 rounds off the high end 486 line up nicely?
Sounds like you have a nice setup for some dos LAN gaming though!

I would think running a 50mhz bus makes this a nice quirky build!

I have no clue what I'm doing! If you want to watch me fumble through all my retro projects, you can watch here: https://www.youtube.com/user/MrDavejustdave

Reply 8 of 9, by jasa1063

Posted on 2021-12-24, 22:16

jasa1063 Offline

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I picked up an OEM Intel DX4/100 to try it out. Going from 50MHz FSB to 33MHz lost some performance in DOS video and system memory throughput, but overall the system is much faster. On the positive side using a 33MHz FSB, I was able to use the lowest memory latency settings. The interesting thing is I could not get the system to POST using the 3V jumper settings documented for this board. I went back to 5V and its working Ok. I have read that the Intel DX4/100 maybe 5V tolerant, but time will tell. I only paid $20 for the CPU from China, so if it stops working after a time, I can put the Intel 486DX/50 back in again. My only real disappointment is that the 16K L1 cache will only operate in write through mode on this motherboard even though the Intel 486 DX/100 CPU I have does support L1 cache write back operation.

Reply 9 of 9, by jasa1063

Posted on 2021-12-25, 01:20

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The documentation online says that JP42 should have Pins 3+5 & 4+6 closed for 5V operation. Looking at the silk screening on motherboard indicates that jumper 3+4 & 5+6 closed is for 3V operation. It's not real clear, but I tried it and the CPU is working. The silk screen is in the attached photo with section highlighted:

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