VOGONS


First post, by lemonlime

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Hi All,

I'm working on a 486 build at the moment. It will be an AMD 486 DX2/80 that will be used mainly for DOS gaming. Right now, I've got a combination VGA and I/O VLB card based on the Trident 9400CXi chipset. It also has an OAK OTI086 chip on the card as well, which I assume may be for basic VGA purposes. The card seems to work well at 40MHz, even without changing the jumper for higher frequency operation.

This is the card here:
https://vswitchzero.files.wordpress.com ... 86_3-6.jpg

It is much faster than an ISA Mach 32 I've tried in the system, but I don't think it's a great card from a VLB perspective. I am thinking of disabling the VGA portion of the card via jumpers and using it for IDE/IO and then using a separate VLB card for graphics purposes. I'm mainly interested in getting the best possible performance out of low-resolution DOS games (Doom, etc). Windows acceleration is a nice-to-have but not my primary concern. Compatibility with some pickier games like Commander Keen would be good as well, as I've had some issues with ATI cards and that title. A decent DAC for image quality would also be a plus. Any recommendations?

Many of the popular ones, including Tseng ET4000 cards are really hard to find here in Canada. I've seen a lot of CL GD5428/5429 cards around that seem to be good performers, as well as some S3 805 based cards.

Thanks!

Reply 1 of 12, by lemonlime

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Actually, looks like I may be mistaken about the Oak Technologies OTI086 chip. It isn't a VGA core like the ones used with Weitek based cards, Seems it is a "Dot Clock Generator" .. "capable of generating up to 16 video clock frequencies and 4 memory clock frequenies" .. "used to replace multiple crystal oscillators to reduce cost". I'm not sure, but I doubt that it would have any negative impact on VGA performance at all.

Reply 2 of 12, by cyclone3d

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Yeah, it shouldn't have anything to do with VGA performance.

Not sure you will really notice much of a difference for DOS stuff with a higher end VLB card.

How much RAM for the vga does it have? If only 1MB, you should be able to upgrade it to 2MB by populating the RAM sockets on the card.

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Reply 3 of 12, by lemonlime

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Not sure you will really notice much of a difference for DOS stuff with a higher end VLB card.

Yeah, that's my dilemma. I don't have another VLB card to really compare it with, unfortunately. The Trident TGUI9400CXi isn't supposed to be a very good VLB card, but it is way better than the ISA cards I've tried. I'm just not sure if a faster VLB card will make games like Doom noticeably smoother.

How much RAM for the vga does it have? If only 1MB, you should be able to upgrade it to 2MB by populating the RAM sockets on the card.

It has 1MB. Any idea from the pictures what type of chips I'd need for this or where would be a good place to source it?

Reply 4 of 12, by SirNickity

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In DOS, there's really not a big difference. The Tseng ET4000 is a bit over-hyped, IMO. It was a fast series of chips for ISA, but the VLB version is just kinda middle of the road. A Cirrus card will give you great compatibility and plenty of performance. They're also easier to find.

I have an ATI Mach64, which is fast but not really much faster than some of my other cards. It has great Windows drivers and made a huge difference back when I got one for my brand new 486DX2/66. AVI files played so smooth!

Reply 5 of 12, by lemonlime

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Thanks for the info about the ET4000, SirNickity. That's good to know.

I may try with the Trident card to see how it goes. I've never run it with a CPU as fast as a DX2/80 so I'm hoping the extra CPU power may help too. I found some 70ns DRAM DIP-20 ICs on eBay for a good price as well so will try to upgrade to 2MB for some higher resolution support as well.

Reply 6 of 12, by mpe

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I own at least two dozens of VL-Bus card. My experience is that in DOS, unless you pick a really wrong one there is nothing to write home about. It is all about interface speed and several cards can saturate that and give you almost identical performance. In Windows there are more substantial difference between different chipsets due to different acceleration, DAC, memory types, etc.

If all you want is to experience DOS you can pick pretty much anything, incl. CL-GD542x. If you are obsessed about small performance gains and performance tuning (like most of us here), then the safe bet is tier-1 card which is one that using this chipsets:

ET4000 w32i/p, Mach64, S3 864/868/964/968, Trio 64, ARK 1000/2000. On used market these tend to be pricier than cards with other chipsets.

To give you and idea what the difference is like:

ZoBxLuQ.png

My retrobuilds:
486DX-50 EISA|NexGen Nx586

Reply 8 of 12, by The Serpent Rider

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It all boils down to which CPU you use. With DX2-80 the difference between cards is negligible, but with AMD 5x86-160 it could be much more profound in some games. And not all top tier cards are on friendly terms with 40Mhz VLB bus.

Reply 9 of 12, by Unknown_K

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The Diamond Viper VLB Witek 9000 isn't even used in DOS, you have a cheap Weitek VGA chip or an Oak Technology OTI087X using its RAM under an 8 bit path so DOS speed sucks.

I have one of those IDE/Serial/VGA boards from Seanix Technologies with the WD90C33 VGA chip and didn't know it was decent in DOS.

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Reply 10 of 12, by mpe

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Unknown_K wrote on 2019-12-31, 05:05:

The Diamond Viper VLB Witek 9000 isn't even used in DOS, you have a cheap Weitek VGA chip or an Oak Technology OTI087X using its RAM under an 8 bit path so DOS speed sucks.

I have one of those IDE/Serial/VGA boards from Seanix Technologies with the WD90C33 VGA chip and didn't know it was decent in DOS.

The Weitek 9000 can be actually used in DOS in VESA modes if you load VESA driver or UniVBE (notice the competitive score in PCBENCH 640x480). However, VGA modes are handled by Weitek 5186 that sits on ISA bus and thus the poor results in other tests.

My retrobuilds:
486DX-50 EISA|NexGen Nx586

Reply 11 of 12, by The Serpent Rider

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However, VGA modes are handled by Weitek 5186 that sits on ISA bus and thus the poor results in other tests.

You can force Build engine games to use VESA 320x200 mode. It also will provide performance boost on normal cards.

Reply 12 of 12, by lemonlime

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Thanks everyone for the information. In the end, I decided to just keep the Trident card. I found some cheap DRAM on eBay and upgraded it to 2MB successfully.

https://pbs.twimg.com/media/EOP0HIuWkAE ... =4096x4096
https://pbs.twimg.com/media/EOP0HItXUAg ... =4096x4096

At 80MHz and a 40MHz bus, Doom runs surprisingly well. In fact, it's noticeably smoother than at 66/33MHz. There is a jumper for >33MHz operation on the card, which I assume adds a wait state, or increases a divider or something. Thankfully it runs fine without it at 40MHz. Seems the extra bus speed increases the memory throughput of the Trident card quite a bit. As an added bonus, compatibility with some pickier games seems to be great - especially keen4/5 etc.

Just waiting on a proper heatsink for my 5 volt DX2-80. This thing runs SUPER hot. I can see why they transitioned to 3V CPUs at around this time.