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Graphics adapter suggestion for a 486 DOS PC

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First post, by nimruil

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Hello guys,

I have an old PC from'93 which i recently modified a bit to play my childhood DOS games a bit better. I added some ram and a sound card. I would like to play games like Hexen, Doom, Doom2 with as much FPS as possible (35 is the max. if i remember correct). I don't plan to play any game from 1996 and afterwards with this PC. Right now there is an obviously low FPS while playing hexen and doom. Reducing the screen size increases the FPS to a much better point. I haven't tried doom2 yet.

Specs:
-HP Vectra VL2 4/66
-D3126-630011 mobo
-intel 486 DX2 66
- 640 KB SYSMEM, 15360 KB EMS
- First level cache 8 KB (not sure about this one but HWINFO says so)
- CL-GD5428-80QC-A 1 mb VLB graphics card with VESA support
- CT2950 non-opl sound card
-540 mb hdd
- 4 ISA slots (1 is being used by CT2950)
- MS-DOS 6.22 & no windows

I can increase the ram to 32 mb, but i think it would be a bit overkill. I can also replace the CPU with an intel DX4/100. What do you think? Looking forward to your opinions.

PS: Sorry if i did any language mistakes as it's not my native language.

Reply 1 of 22, by nimruil

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Forgot to write, i found the 3 videos cards of which i posted photos. would they increase performance?

Reply 2 of 22, by The Serpent Rider

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Not sure it would be beneficial, if internal 5426 chip is connected via VLB. Especially when it comes to Doom, if you're not using FastDoom source port.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 3 of 22, by jakethompson1

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The Serpent Rider wrote on 2024-09-08, 16:54:

Not sure it would be beneficial, if internal 5426 chip is connected via VLB. Especially when it comes to Doom, if you're not using FastDoom source port.

Agreed, this doc on page 195 says the IDE is local bus: https://theretroweb.com/motherboard/manual/19 … 47041054379.pdf

It would be really odd to put IDE on local bus but not video, although it doesn't make such claim in the next column about the video.

If the video is local bus, it's better than any ISA card you can install.

Reply 4 of 22, by Namrok

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So, I have a GD-5428 VLB card in my 486 DX2, and what was holding back my Doom performance the most was poor memory timings. My BIOS was kind crap too, so I ended up using a utility called AMISETUP to access them. After I got everything tuned, it ran Doom just about as well as any other DX2 I saw in benchmarks. I'd wager you won't do much better in the VGA department for Doom and the like until you move onto a PCI based system with a Pentium chip.

Win95/DOS 7.1 - P233 MMX (@2.5 x 100 FSB), Diamond Viper V330 AGP, SB16 CT2800
Win98 - K6-2+ 500, GF2 MX, SB AWE 64 CT4500, SBLive CT4780
Win98 - Pentium III 1000, GF2 GTS, SBLive CT4760
WinXP - Athlon 64 3200+, GF 7800 GS, Audigy 2 ZS

Reply 5 of 22, by Disruptor

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A Cirrus 5428 should be one of the faster VLB cards (not fastest).
Your ISA graphics cards are in the lower range of speed.

Finding AMISETUP to optimize settings is a good idea. Just make some stability tests too.

What's about second level cache? Or is that black socket between CPU and memory for a second level cache?

For a DX4 you need a VRM (voltage regulation) system that converts 5 Volt to 3.3 Volt.

I'd say, keep the 16 MB RAM.

Reply 6 of 22, by nimruil

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The Serpent Rider wrote on 2024-09-08, 16:54:

Not sure it would be beneficial, if internal 5426 chip is connected via VLB. Especially when it comes to Doom, if you're not using FastDoom source port.

I thought so. Fastdoom would help quite a bit, but i am planning to keep it old school as much as possible for nostalgia purposes.

jakethompson1 wrote on 2024-09-08, 17:24:

If the video is local bus, it's better than any ISA card you can install.

I double checked this in HWINFO before posting, it says it's VLB.

Disruptor wrote on 2024-09-08, 17:58:
A Cirrus 5428 should be one of the faster VLB cards (not fastest). Your ISA graphics cards are in the lower range of speed. […]
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A Cirrus 5428 should be one of the faster VLB cards (not fastest).
Your ISA graphics cards are in the lower range of speed.

Finding AMISETUP to optimize settings is a good idea. Just make some stability tests too.

What's about second level cache? Or is that black socket between CPU and memory for a second level cache?

For a DX4 you need a VRM (voltage regulation) system that converts 5 Volt to 3.3 Volt.

I'd say, keep the 16 MB RAM.

I think there is no second level cache. I just checked, according to the manual that black slot is for a cache upgrade. Honestly I am not even sure how they look like or what i should be looking for specs wise. I am also not sure if it will affect performance.

About VRM, manual says pc is DX4 compatible, would i still need a VRM in this case?

Reply 7 of 22, by leileilol

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I think the video's fine. More RAM won't help much. The CPU could use a bump, but there's also concerns of that on VLB (i.e. risking corruption or damage to video cards when you try all the fun clockspeeds for AM5x86)

A 486 DX2/66 was a desired average gaming system for 1994 so there'd be many here who wouldn't change a thing but capacitors. 😀

apsosig.png
long live PCem

Reply 8 of 22, by dormcat

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nimruil wrote on 2024-09-08, 16:44:

PS: Sorry if i did any language mistakes as it's not my native language.

Welcome, and no need to worry about that; saw that 英雄联盟 (LoL) mousepad in the background. 😉

As the framerate question: IMHO the Doom engine used by all three games preferred faster CPU than graphic chips, and your Vectra VL2 4/66 only has an all-ISA riser card so any ISA graphics card is unlikely to be faster than the integrated CL-GD5428-80QC-A. There are PCI riser cards available for Vectra series but I don't know if they are compatible with your system. So I'd suggest

  1. Find a faster and compatible CPU.
  2. Find a compatible PCI riser card (if any) and a PCI graphics card, along with a faster and compatible CPU.
  3. Find another system that had better upgradability in mind rather than an office computer.

Doom engine had minimal issues with faster computers (I've played those on Pentium-MMX 233MHz and 64MB RAM without problems) so you don't have to limit your choice to pre-Pentium builds as working builds are more difficult to find and expensive to buy.

Reply 9 of 22, by florian3

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nimruil wrote on 2024-09-08, 18:33:

About VRM, manual says pc is DX4 compatible, would i still need a VRM in this case?

If the board is compatible then you should see voltage regulator components near the CPU socket and a jumper to set the voltage.

There are also DX4 overdrive processors that include the VRM.

Reply 10 of 22, by mkarcher

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florian3 wrote on 2024-09-08, 22:08:

If the board is compatible then you should see voltage regulator components near the CPU socket and a jumper to set the voltage.

Not all 3.3V compatible 486 boards include a jumper to set the voltage: The 3.3V processors have a pin called "VOLDET" grounded that is not connected on 5V processors. Some boards use that pin to automatically switch to 3.3V if a 3.3V processor is inserted. Having a jumper obviously is a clear sign of 3.3V support, though.

Reply 11 of 22, by BinaryDemon

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I wouldn’t change video cards, check VLB wait state setting and see if you can go lower.

Use FastDoom for Doom/Doom2, won’t help with Hexen.

Upgrade CPU- 486 DX4-100, Pod83, or 586-133 with interposer are all good options.

Reply 12 of 22, by jtchip

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nimruil wrote on 2024-09-08, 18:33:

I think there is no second level cache. I just checked, according to the manual that black slot is for a cache upgrade. Honestly I am not even sure how they look like or what i should be looking for specs wise. I am also not sure if it will affect performance.

About VRM, manual says pc is DX4 compatible, would i still need a VRM in this case?

The service handbook linked above does list the part numbers for the 128K and 256K cache memory upgrade kits on page 196. This will increase performance, games typically have working sets that are larger than the 8K L1 cache.

On page 199, it mentions:

  • JP12 (VL2 DX4 models only) Reserved for factory use - do not move.

Does your motherboard have a JP12? It probably selects 3.3V operation but it's not clear whether all models come with a VRM or only the VL2 4/100 model. On page 202, the VL2 DX4-100 has a different part number for the system board, which may mean that only that model has the VRM. One way to be sure is to remove the CPU, find the VCC pin on the socket, and measure it with JP12 in either position.

Also on the same page, the processors listed are all SL variants, not sure what this means for a desktop computer.

Reply 13 of 22, by chinny22

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nimruil wrote on 2024-09-08, 16:44:

games like Hexen, Doom, Doom2 with as much FPS as possible (35 is the max. if i remember correct)

I think you forget we didn't care about FPS when we were young.

Large maps on Doom 2 defiantly slow down on a dx2/66
Heretic is about the same but Hexen is playable but definitely not smooth.

Phil did a benchmark project few years back, you can check your scores against similar PC's and see if your much slower.
https://docs.google.com/spreadsheets/d/1lvF9n … dit?gid=0#gid=0

Reply 14 of 22, by Namrok

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chinny22 wrote on 2024-09-09, 02:11:
I think you forget we didn't care about FPS when we were young. […]
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nimruil wrote on 2024-09-08, 16:44:

games like Hexen, Doom, Doom2 with as much FPS as possible (35 is the max. if i remember correct)

I think you forget we didn't care about FPS when we were young.

Large maps on Doom 2 defiantly slow down on a dx2/66
Heretic is about the same but Hexen is playable but definitely not smooth.

Phil did a benchmark project few years back, you can check your scores against similar PC's and see if your much slower.
https://docs.google.com/spreadsheets/d/1lvF9n … dit?gid=0#gid=0

So that's actually the spreadsheet I was comparing myself against with my DX2. I was about 15% off until I tuned the BIOS. I finally found the laminated sheet I though I had kept with my 486 where I recorded the specific settings I applied in AMISETUP. They were stable for me, but your mileage may vary. I actually think my ram and cache is too slow for most of them, but I think the crappy knockoff chipset my PC Chips motherboard uses slows things down enough on it's own where it just sort of works anyways. It's never shown any instability at least.

Cache Read Option: 2-1-1-1
Cache Write Option: 0 WS
DRAM Type: FastPage
DRAM Wait States: 0 WS
Fast Gate A20 Option: Enabled
IDE Block Mode: Enabled

Win95/DOS 7.1 - P233 MMX (@2.5 x 100 FSB), Diamond Viper V330 AGP, SB16 CT2800
Win98 - K6-2+ 500, GF2 MX, SB AWE 64 CT4500, SBLive CT4780
Win98 - Pentium III 1000, GF2 GTS, SBLive CT4760
WinXP - Athlon 64 3200+, GF 7800 GS, Audigy 2 ZS

Reply 15 of 22, by Disruptor

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Namrok wrote on 2024-09-09, 17:10:
Cache Read Option: 2-1-1-1 Cache Write Option: 0 WS DRAM Type: FastPage DRAM Wait States: 0 WS Fast Gate A20 Option: Enabled IDE […]
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Cache Read Option: 2-1-1-1
Cache Write Option: 0 WS
DRAM Type: FastPage
DRAM Wait States: 0 WS
Fast Gate A20 Option: Enabled
IDE Block Mode: Enabled

First 2 options do not apply to his system as he does not have any L2 cache.

Last edited by Disruptor on 2024-09-10, 21:23. Edited 1 time in total.

Reply 16 of 22, by nimruil

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Guys, thank you very much for pitching in and providing your insights on the topic. It looks like using the on-board VLB card is the best course of action considering the circumstances.

jtchip wrote on 2024-09-08, 23:16:
The service handbook linked above does list the part numbers for the 128K and 256K cache memory upgrade kits on page 196. This w […]
Show full quote

The service handbook linked above does list the part numbers for the 128K and 256K cache memory upgrade kits on page 196. This will increase performance, games typically have working sets that are larger than the 8K L1 cache.

On page 199, it mentions:

JP12 (VL2 DX4 models only) Reserved for factory use - do not move.

Does your motherboard have a JP12? It probably selects 3.3V operation but it's not clear whether all models come with a VRM or only the VL2 4/100 model. On page 202, the VL2 DX4-100 has a different part number for the system board, which may mean that only that model has the VRM. One way to be sure is to remove the CPU, find the VCC pin on the socket, and measure it with JP12 in either position.

Cache upgrades: I couldn't find anything with those part numbers. I watched LGR's video on youtube, he uses individual chips for this but my PC obviously has a slot near RAM slots for this upgrade. I found one in ebay but i'm not sure if they are suitable or not. I don't want to do something wrong and harm the PC.

https://www.ebay.com/itm/325909219761?_nkw=25 … pte_vbtk&edge=1

JP12: I checked it and i see that there is indeed a JP12 jumper. I will add photo of it as an attachment. I don't exactly understand how to measure VCC with JP12 but i will add a photo of CPU. Sorry for being such a noob 😀 These are new subjects to me.

I'd like to say this PC goes as VL2 4/66 (as in, it can have a dx4 processor maybe?). Also, probably this is a very noob question but, can i add an amd dx4 processor instead of intel dx4? I will add photos of both processors in attachment.

chinny22 wrote on 2024-09-09, 02:11:

I think you forget we didn't care about FPS when we were young.

https://docs.google.com/spreadsheets/d/1lvF9n … dit?gid=0#gid=0

I definitely didn't forget. I just wanted to have an improved experience, since i am not the same kid who had to ask his parents to buy a better PC so he can play games better anymore. I am the same kid who just has more money than that time now so he can try what he couldn't try before 😀)) But i see your point.

Reply 17 of 22, by jtchip

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nimruil wrote on 2024-09-10, 12:35:

Cache upgrades: I couldn't find anything with those part numbers. I watched LGR's video on youtube, he uses individual chips for this but my PC obviously has a slot near RAM slots for this upgrade. I found one in ebay but i'm not sure if they are suitable or not. I don't want to do something wrong and harm the PC.

https://www.ebay.com/itm/325909219761?_nkw=25 … pte_vbtk&edge=1

That won't work, the seller even got the part number wrong (the second last '3' should be an '8'). It looks like a COASt (Cache on a stick) module and it's pipeline burst cache, which AFAIK no 486 chipset supports, so it's probably for a Pentium with at least an i430FX (Triton) chipset. Your VL2 needs a proprietary cache module and it really must use the correct part number.

nimruil wrote on 2024-09-10, 12:35:

JP12: I checked it and i see that there is indeed a JP12 jumper. I will add photo of it as an attachment. I don't exactly understand how to measure VCC with JP12 but i will add a photo of CPU. Sorry for being such a noob 😀 These are new subjects to me.

I'd like to say this PC goes as VL2 4/66 (as in, it can have a dx4 processor maybe?). Also, probably this is a very noob question but, can i add an amd dx4 processor instead of intel dx4? I will add photos of both processors in attachment.

No, it doesn't mean that as the +3.3V VRM means extra components and HP could have decided to just omit those on anything that's not a 4/100 model. You could try to follow the traces from JP12 to see if they end up at a VRM.

To measure the voltage, you need to find the Vcc pins. Scrap Computing designed a 486SocketBlaster 3V adapter and has a video, at 1:09 is the pinout of the 486 socket and at 10:30 he shows the voltage being measured. Although if you're unsure about doing this, please don't in case you damage something by e.g. short circuit.

The AMD DX4 may or may not work, depending on how fussy the BIOS is. The Intel DX4 has 16K L1 cache in either write-through or write-back (your picture shows the write-through variant). The AMD DX4 has 8K write-through L1 cache, unless it's the enhanced variant which can have either 8K or 16K writeback L1 cache (your picture shows the enhanced variant with 8K writeback).

Reply 18 of 22, by Disruptor

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jtchip wrote on 2024-09-10, 23:32:

The AMD DX4 has 8K write-through L1 cache, unless it's the enhanced variant which can have either 8K or 16K writeback L1 cache (your picture shows the enhanced variant with 8K writeback).

The Am486DX4 SV8B on the picture is the write-back variant and has to be jumpered like DX4 (Enhanced AMD). Write through are V8T or NV8T and have to be jumpered like DX2 (Standard 486) but with 3.3 Volt too.

Reply 19 of 22, by florian3

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The part in the bottom left of "current cpu front.jpg" looks like a voltage regulator with heatsink.
But before trying to use a 3.3V CPU you would definitely have to find out what JP12 does and measure the voltage.
JP10 which is right next to JP12 in "photo_2024-09-10_14-45-38.jpg File size" is labeled WB/WT, so probably allows you to select between write-through and write-back.