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S3 Vision 968 VLB replica

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Reply 40 of 56, by Madao

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Yes, i was with 14 Chip. It is planning in dosforum with ~ 12 people.

Trio64V+, i would make it. Main goal is ViRGE VL , which their chip is pin compatible with Trio64V+. Probably fastest VLB video card for DOS.
VL-Mode at ViRGE & Trio64V+ = max 2 MB RAM. Trio64V+ & ViRGE has only 135Mhz DAC , despite this fact, it is good chip from their time.

I have check 968VL performance on 486DX2-66 w. PAT48AV Board , this mainboard has very good memory output.
By 66Mhz clock: no difference with S3 Trio64. I must check with faster CPU ( PAT48AV haven't 3.3V regulator 🙁 )

Soon , not today, i check 968VL card with Vision964 chip. This Chip is much better avaible. (but not cheap, better as nothing)

Greetings
matt

Reply 41 of 56, by TheMobRules

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Nice! Looking forward to how the Virge project turns out!

It may be just an impression, but my Trio64 VLB seems to have better display quality than my #9 Vision968 PCI... my 968 has the IBM DAC though, maybe the TI DAC is better?

Reply 42 of 56, by The Serpent Rider

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IBM DAC - 175 Mhz, TI DAC - 220 Mhz.

Madao wrote on 2020-09-30, 17:59:

By 66Mhz clock: no difference with S3 Trio64. I must check with faster CPU ( PAT48AV haven't 3.3V regulator 🙁 )

I have S3 Trio64 PCI clocked at 70 Mhz in my testing, which outperforms S3 Vision 968 easily in DOS: PCI Video cards benchmark: Electric Boogaloo Edition

Get up, come on get down with the sickness
Open up your hate, and let it flow into me

Reply 43 of 56, by Madao

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I know, Trio64 is very fast card in Text/VGA-Mode..
It make with DX2- 66 no difference, it is just a CPU limit. Difference would be better visible, if CPU is much faster.
I have already wroten: Vision968 is not superior in VGA/Text-Mode, because it run same as convontial DRAM video card. Their strength is Windows (GUI & 2D-Acceleration)

Trio64 and successor has more agressive RAM timing, this is one of more reason for superior performance in text/VGA Mode.
But i can tell: Vision968 (not other, only 968) is capable to driving agressive RAM. I haven't checking it.

Your avatar, i know, which anime: dorohedoro. 😉

Grettings
matt

Reply 44 of 56, by PC-Engineer

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The Serpent Rider wrote on 2020-09-30, 19:03:

IBM DAC - 175 Mhz, TI DAC - 220 Mhz.

Cannot be true, I have a Stealth 64 Video PCI with 220MHz IBM DAC and a Spea Mercury PCI with 175MHz TI DAC.

1994/1995 - Socket3 - ASUS SV2GX4 / POD 100MHz / 64MB / SCSI - Windows 95

Reply 45 of 56, by The Serpent Rider

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Diamond had exactly 175 Mhz IBM DAC on their cards, which is well documented - http://vgamuseum.info/index.php/component/k2/ … am-s3-vision968

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Reply 46 of 56, by Doornkaat

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The Serpent Rider wrote on 2020-10-01, 19:01:

Diamond had exactly 175 Mhz IBM DAC on their cards, which is well documented - http://vgamuseum.info/index.php/component/k2/ … am-s3-vision968

Dude, even in the page you're referencing there are pictures of 175MHz as well as 220MHz Ti DACs. datasheet
All IBM DACs in the pictures are 37RGB526 CF 22 which is the IBM 220MHz DAC. datasheet

Reply 48 of 56, by mpe

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I happen to own Diamond Stealth 64 Video PCI in both 175 and 220 MHz TI RAMDAC version:

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There is hardly any difference in quality. The later can do 1024x768 @ 120 Hz, 1280x1024 @ 100 Hz and especially 1600x1280 @ 76 Hz which was a big deal back then in CRT era.

The IBM part can be had in either IBM RGB514 (170 MHz) or RGB524 (220 MHz) version and I think I've seen them both on a Stealth64 VRAM card.

Blog||486DX-50|NexGen 586|S4

Reply 49 of 56, by The Serpent Rider

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All IBM DACs in the pictures are 37RGB526 CF 22

Yeah, I didn't checked photos for IBM thoroughly, my card has 170 Mhz DAC.

Dude, even in the page you're referencing there are pictures of 175MHz as well as 220MHz Ti DACs.

I had no argue with that.

I thought people is saying IBM DAC is not good quality vs TI DAC?

From my experience: IBM DAC has some issues with LCD monitors, lowres modes are unstable.

Get up, come on get down with the sickness
Open up your hate, and let it flow into me

Reply 50 of 56, by Madao

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Diamond Card, most PCI card with 175Mhz DAC is OEM-card, which 220Mhz card is retail-version.
D7-Revision has few design fail (non functional DDC interface , TTL input open) maybe E-Revision is better.

I don't know about IBM DAC signal quality, but i wouldn't make a card with him: no datasheet (only partial datasheet found )

I have checked with Vision964 Chip on card: Textmode look wreid, the rest works.. i am confused, probably no CGA, MDA, HGC support. Despite, i use Vision968 bios..

Reply 52 of 56, by pentiumspeed

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Ok go for 50MHz. Might want to check every trace for noise and clean them up properly that original designers of the VLB video card skimped on to bring under budget?

Cheers,

Great Northern aka Canada.

Reply 53 of 56, by Madao

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This is next step, but i haven't DX50 here. It is storaged at other location (parent's farm)

4 layer design is a gain for stable high clock. 50Mhz clock PCB Trace is not very critical, if you keep trace-lenght similar (max 1-2 cm difference by lenght )

Greetings
matt

Reply 54 of 56, by pentiumspeed

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If you have to, make zig-zag traces for the key timing tracks and clocks to make lengths same or adjust the timing by this method. Commonly done on memory circuits.

Use a 5V AMD 486DX 40 and overclock from there with heatsink & fan. This what I had back in the day, overclocked to 50, wonderful on SiS 461 or 471 chipset motherboard.

I would appreciate also design a VLB multi-i/o card in 4 layers and use best chips and fully buffered. This success works best for 50MHz fsb. boards makers left out design recommendations when designing boards. Power planes done right, Arranging tracks correctly, and stick to chipset datasheets recommendations like if it requires specific reference voltage via divider circuit which is not stable, rather use a low current small regulators instead and make that reference voltage so ultra clean beyond minimum recommandations, put resistors and inductors on some important signals to clean up signal waveforms and reduce loading from the processor pins. Double capacitor (10uF for bulk and high frequency 1uF instead of one capacitor. Compaq used 3 SMD capacitors in parallel at each capacitor location.

Cheers,

Great Northern aka Canada.

Reply 55 of 56, by Madao

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Hello

Correct, but here with only 50Mhz cycle isn't zig zag trace needed. Important: keep PCB Trace lenght similar (few cm difference is not problem)

Here a drawing of bracket for 968VL. But i am not 100% sure with bracket_968VL.pdf , because it fit well in old AT-case . By ATX-case exists half millimeter gap.

bracket_968VL_01.pdf is modified for 100% safe fitting. (1.6mm moved )

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Reply 56 of 56, by fry35

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Would it be too demanding to produce another board, and how much would it cost if you agree?

I am looking for a vision968 vlb for almost two years now. I have some 964 vlb boards from spea, diamond, #9 and miro. Only a couple are 4MB.