VOGONS


First post, by Hezus

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Thought it would be fun to do another build log! This time around I'm putting together a 486 to help me with some issues I've encountered on my regular DOS machine, which is a Pentium 233. Some older games do not run great and I've especially got trouble starting certain games that were ported to the PC, such as Cannon Fodder or First Samurai.

Let's start with the case. This AT case has no brand, only a type number: ST-460. The front is slightly yellowed but otherwise is in great condition. The panel has HDD and Power LEDs, reset button and a key lock (for which I lack the key, sadly). The sticker says RAM 486, which is probably the company that put it together initially.

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PSU is this 200W unit from East. Plenty of power for this system!
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Onto the hardware! I'm using this motherboard from DATAEXPERT. It's the 8049 REV 1.1A and is a great 486 board from the later era. It has ISA, PCI and an on-board HDD controller. The CMOS battery is a barrel variant, but it's still in great condition.

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If you pay close attention, you'll notice that the motherboard mentions it has the best performance with an AMD CPU. So, let's do so and we're putting in the Am486-DX4 running at 100 Mhz. A heatsink is required, so let's put that on.

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Putting it into the case is a bit of a hassle.The case only has 2 standoffs for the motherboard and is held in below by a plastic bar. You'll have to slide this onto the motherboard and then put it back into the case.

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The plastic bar makes it a VERY tight fit but with some effort it's finally in there quite firmly. It's a cost saving method but just drilling in 2 additional standoffs would have been far more convenient.

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Already inserted are these two bars of 72 pin RAM (no brand). 4 mb each gives the system a grand total of 8 mb which is fine for what I'm using it for. The motherboard supports up to 64 mb, so there is always room for more.

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A 486 surely requires some COM ports, so here are two serial connectors.

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Time for some drives! A:\ will be this Sony MPF920-E (3,5" 1,44 MB) and B:\ is the Panasonic JU-475-4AGJ (5.25" 1.2MB). I would rather have a beige front to go with the rest of the case, but this is all I had laying around.
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The C:\ drive consists of the Seagate Medalist 8420 (ST38420A), giving me a whopping 8.6 Gb of storage. D:\ will be this Wearnes CDD-120A.

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Let's put it all drives in, attach all cables and see what we've got:

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Well, seems we've got CABLE MANAGEMENT HELL! I'll be able to fix that up with some wires but another great trick is to slice up the IDE cables and bundle them together. This makes is far easier to route them through the system and tuck them away.

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And this is much more manageable!

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Let's start picking some cards. For the videocard I've got the choice between the S3 Trio32 and the Tseng Labs ET4000AX. The first is a relatively fast PCI card which would make some more demanding games run fast. However, I already have a better system for that and I'm looking for compatibility with some older and tricky to run games. That's why I'm going with the ET4000AX for the ISA slot.

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For sound I'm using the ESS Audiodrive ES1868F. It has great Sound Blaster Pro compatibilty, which a lot of the games I'm targeting use.

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Lastly I'm adding this 3COM 3C905-TX network card for easy file transfer.

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And here's the system with all the parts put together and finally assembled with the top cover back on it.

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It runs fine and the games I've had trouble playing on my pentium give me no grief on this 486! I'm pretty happy with the system but I've got some whishes and plans for down the road:

- Replace the barrel battery with a coin cell.
- Drill in 2 stand-offs and get rid of the stupid plastic bar.
- Create a new front panel with a turbo button and an LCD display. I've got the hardware but I would have to get into 3D printing to make my own bracket.
- Swap the 5,25" for a different drive with a beige plate for aesthetics.
- Use CF storage instead of a HDD. The BIOS doesn't want to play nice with the CF adapters I've got. I might be able to load an XT-IDE BIOS into the ROM of the network card and get it to work that way.
- Increase the RAM to 16 mb just for kicks.

Thanks for reading my build log and if you've got some suggestions for the system, feel free to post them 😀 If you've enjoyed this, also check out my Pentium II build.

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Reply 2 of 21, by Hezus

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maxtherabbit wrote on 2021-11-27, 22:42:

Not using a PCI video card in a PCI 486 is a criminal act of heresy

Me yesterday: let's put in the effort of taking a lot of pictures building this pc and share it with other enthusiasts on the internet for mutual fun.

Me today: gets snarky comments by people who do not bother to read.

Yeah, Vogons is a great place.

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Reply 3 of 21, by Blavius

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Cool build man! Love the Tseng 4000, had that one in my 486 back in the day 😀 Are you running windows 95 for the networking, or do you do everything in DOS?

Reply 4 of 21, by Hezus

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Blavius wrote on 2021-11-28, 09:08:

Cool build man! Love the Tseng 4000, had that one in my 486 back in the day 😀 Are you running windows 95 for the networking, or do you do everything in DOS?

Thanks! The ET4000 sure is one of the best ISA cards you can get 😀

The networking is all in DOS using Mtcp. Because this system is for compatibility, I'm trying to keep this pure DOS (running 6.22 now).

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Reply 5 of 21, by 8bitbubsy

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Nice system, though remember that AMD DX4-100 only has 8kB L1 cache vs. 16kB on the Intel DX4-100.
That mobo text just sounds like an AMD advertisement to me (probably referring to the AMD P75 133MHz CPU).

Also, using an ISA graphics card in a late 486 system should've been illegal! Wouldn't it be better to just get a 486 VLB mobo then? Both good compatibility, and much faster video performance in DOS games.

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz
- RAM: 16MB 60ns FPM
- VGA: S3 Vision864 2MB VLB
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card
- ISA USB
- MS-DOS 6.22 + WfW 3.11

Reply 6 of 21, by Hezus

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8bitbubsy wrote on 2021-11-28, 11:09:

Nice system, though remember that AMD DX4-100 only has 8kB L1 cache vs. 16kB on the Intel DX4-100.
That mobo text just sounds like an AMD advertisement to me (probably referring to the AMD P75 133MHz CPU).

Also, using an ISA graphics card in a late 486 system should've been illegal! Wouldn't it be better to just get a 486 VLB mobo then? Both good compatibility, and much faster video performance in DOS games.

As I've mentioned above , I've got a Pentium 233MMX system that handles DOS games with great performance. This 486 is mainly for playing older titles that will not work right on that Pentium, therefore I'm keeping it low end on purpose.

I know we all get excited about maxing out a system, but that's not what its intended use case is.

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Reply 7 of 21, by Doornkaat

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Good looking case you got there!
Also good job managing those cables. That's always a chore on AT systems. Well done!👍
I've never seen that plastic rail or anything like it to secure the mobo before. If the mobo fits I'd just leave it like that to keep it slightly odd.😉

Last edited by Doornkaat on 2021-11-28, 11:36. Edited 1 time in total.

Reply 8 of 21, by 8bitbubsy

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Here's a good tip for compatibility with old DOS games: Clock the CPU down to like 16-25MHz, and disable L2 cache.

Last edited by 8bitbubsy on 2021-11-28, 12:01. Edited 2 times in total.

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz
- RAM: 16MB 60ns FPM
- VGA: S3 Vision864 2MB VLB
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card
- ISA USB
- MS-DOS 6.22 + WfW 3.11

Reply 9 of 21, by Hezus

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Doornkaat wrote on 2021-11-28, 11:33:

Good looking case you got there!
Also good job managing those cables. That's always a chore on AT systems. Well done!👍
I've never seen that plastic rail or anything like it to secure the mobo before. If the mobo fits I'd just leave it like that to keep it slightly odd.😉

Thanks! 😀 Yeah, that plastic rail is a really odd way of securing a mobo. Let's hope I don't have to swap mobos any time soon because it's a b*tch to work with.

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Reply 10 of 21, by maxtherabbit

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Hezus wrote on 2021-11-28, 08:47:
Me yesterday: let's put in the effort of taking a lot of pictures building this pc and share it with other enthusiasts on the in […]
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maxtherabbit wrote on 2021-11-27, 22:42:

Not using a PCI video card in a PCI 486 is a criminal act of heresy

Me yesterday: let's put in the effort of taking a lot of pictures building this pc and share it with other enthusiasts on the internet for mutual fun.

Me today: gets snarky comments by people who do not bother to read.

Yeah, Vogons is a great place.

who says I didn't read?

anyway cope

Reply 11 of 21, by Hezus

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8bitbubsy wrote on 2021-11-28, 11:34:

Here's a good tip for compatibility with old DOS games: Clock the CPU down to like 16-25MHz, and disable L2 cache.

Indeed a good way to handle speed sensitive games, although I haven't had any issue with that so far. Unless it's the really old ones, but I've got an 8088 for those 😀

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Reply 13 of 21, by Hezus

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octopus wrote on 2021-12-27, 20:44:

Nice build there, love the pictures.
I'm going to start a 486 build, and it's my first 'from scratch'.
You make it look easy, so that's comforting!

Thanks! I went out of my way to get it all photographed, so it makes for an entertaining thread 😀

486s are actually relatively complex, since they had such a long lifespan and saw many new experimental technologies that came and went even during its own lifetime. There are late 486 boards that have nearly everything integrated just like a modern motherboard, and really old ones that require a separate expansion card just to have hard drive support.

The trickiest part of building a 486 surely are the CPU jumper settings. There were so many different types of 486 CPUs, that you have to be very careful to set up your jumpers right. Make sure you find the manual to your board before you attempt anything. Worst case scenario, you set your 3.3v CPU to 5v and blow it up.

A manual can also help a lot finding the right headers for those LEDs and buttons on your case.

Good luck with your build! Don't hesitate to ask questions if you're in doubt.

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Reply 15 of 21, by Hezus

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Luke4838P wrote on 2022-05-07, 19:39:

Sorry for the necro.
I also have acquired the same motherboard (exp 8049 rev 1.1a) and was interested in knowing if you succeeded in making the cr 2032 modification.

No, I left the battery on there for now. It should be quite easy to replace it, though. You just got a find a good spot to attach the battery holder.

Could you be so kind to dump a copy of your BIOS? I accidentally bricked mine and could not find the exact bios. I managed to make it work with a slightly older version, but the v1.1 isn't available anywhere. Would be great to restore it to its original state.

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Reply 16 of 21, by Luke4838P

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Hezus wrote on 2022-05-09, 14:17:
Luke4838P wrote on 2022-05-07, 19:39:

Sorry for the necro.
I also have acquired the same motherboard (exp 8049 rev 1.1a) and was interested in knowing if you succeeded in making the cr 2032 modification.

No, I left the battery on there for now. It should be quite easy to replace it, though. You just got a find a good spot to attach the battery holder.

Could you be so kind to dump a copy of your BIOS? I accidentally bricked mine and could not find the exact bios. I managed to make it work with a slightly older version, but the v1.1 isn't available anywhere. Would be great to restore it to its original state.

Is your battery ni-mh or ni-cd?
Because that seems a non rechargeable battery with those colors as I've saw that kind of battery online and it says "DO NOT RECHARGE".
About the bios, how you do make a copy of it?
I've recently removed the glue that held down the barrel battery (it was a green NI-MH 3.6V 60 mAh rechargeable battery) and it shows that the barrel battery leaked acid but fortunately only removed the protective paint.

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Reply 17 of 21, by Hezus

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I can't read the description on the side of the battery without having to take the entire motherboard out. But I can see that mine has a green leaf icon on it with "No Mercury & Cadmium", so I assume mine is also a ni-mh battery. And it doesn't like Queen.

There are several tools to grab the BIOS: https://www.dosdays.co.uk/topics/bios.php

BIOS (v1.35.1) should be an easy-to-use program. Sorry to ask you to go through all this hassle, but you might be the last person on earth to have access to this particular BIOS version right now, so it's up to you to save the world! No pressure 😉

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Reply 18 of 21, by Luke4838P

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Hezus wrote on 2022-05-09, 17:06:

I can't read the description on the side of the battery without having to take the entire motherboard out. But I can see that mine has a green leaf icon on it with "No Mercury & Cadmium", so I assume mine is also a ni-mh battery. And it doesn't like Queen.

There are several tools to grab the BIOS: https://www.dosdays.co.uk/topics/bios.php

BIOS (v1.35.1) should be an easy-to-use program. Sorry to ask you to go through all this hassle, but you might be the last person on earth to have access to this particular BIOS version right now, so it's up to you to save the world! No pressure 😉

Right now the PC isn't at home, but at work.
I will get it ASAP and boot it up to use that utility to backup the BIOS.
I got it from a seller that had this machine stored for years and still had Windows 95 Plus! on it.
PCI video card with 1mb.
ISA SB sound card.
i486DX4-100 CPU.
A single 3.5" Floppy drive and a malfunctioning CD drive (it won't close completely and keeps opening if closed).
Once fixed that battery problem and made sure at 100% no traces were damaged, i'd install a 5.25" Floppy drive and a good CD-RW drive.
Little problem is that i can't use the mouse as there's no dedicated internal PS/2 Mouse interface (unless it was of weird internal OEM PS/2 interfaces that used COM channels) but only RS-232 (DB-9) interface (i don't own a mouse that old).
When booting, it pops up a setting that says "PS/2 mouse: Not installed".
If i recall correctly, the battery you have should be this one and it's NOT rechargeable.
https://www.vlad.fr/en/batteries/155-ba ... iran.html
Before you unintentionally blow up the motherboard i'd recommend taking off that battery (unless you know that the charging circuit was disabled).
I'd still be interested in having someone help me locate the charging circuit to place a diode and install a nice CR-2032 on it.
Despite measuring the voltage on this PC's old barrel battery that was 0.5V, the BIOS still had time and settings still set as normal.
Fortunately i got that damn barrel battery before it destroyed that motherboard.

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Reply 19 of 21, by Luke4838P

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Bump for a question.
Is the charging circuit here?

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