The motherboard uses AT power. You either need an AT power supply or, an ATX power supply and an ATX to AT power adapter like I do. I consider it safer as I do not trust ancient power supplies. They can blow up and kill your expensive hardware.

Mau1wurf1977 wrote:

The motherboard uses AT power. You either need an AT power supply or, an ATX power supply and an ATX to AT power adapter like I do. I consider it safer as I do not trust ancient power supplies. They can blow up and kill your expensive hardware.

Having your PSU blow is a unique retro experience in itself. 🤣

Kahenraz wrote:

Having your PSU blow is a unique retro experience in itself. 🤣

😀

During my first summer job I was asked to test a ton of old computers. And one CRT monitor blew up on with a loud bang and a huge cloud of smoke. It scarred me for life and any time a CRT monitor would make a funny electrical noise I would jump back. Maybe this is the reason I quickly moved towards LCD monitors.

Looks like the PSU has both ATX and AT connectors? That's really weird!
But plug in the other half of the AT connector. I think it should be P8 and P9. They will sit side by side with the black bunch in the center

smeezekitty wrote:

Looks like the PSU has both ATX and AT connectors? That's really weird!
But plug in the other half of the AT connector. I think it should be P8 and P9. They will sit side by side with the black bunch in the center

I think it's actually just an ATX supply. Some earlier ATX boards/PSUs use a single AT style connector for auxiliary power. I've seen it on some Pentium Pro and P2 boards, not sure if the practice continued much beyond that.

Synoptic: I don't know if the pinout of that aux connector actually matches the corresponding half of an actual AT supply. Be careful of that. If you end up using an ATX->AT adapter, and you find that this extra connector doesn't have the correct pinout, then I'd tape it up to avoid any accidents.

shamino wrote:

smeezekitty wrote:

Looks like the PSU has both ATX and AT connectors? That's really weird!
But plug in the other half of the AT connector. I think it should be P8 and P9. They will sit side by side with the black bunch in the center

I think it's actually just an ATX supply. Some earlier ATX boards/PSUs use a single AT style connector for auxiliary power. I've seen it on some Pentium Pro and P2 boards, not sure if the practice continued much beyond that.

Synoptic: I don't know if the pinout of that aux connector actually matches the corresponding half of an actual AT supply. Be careful of that. If you end up using an ATX->AT adapter, and you find that this extra connector doesn't have the correct pinout, then I'd tape it up to avoid any accidents.

Yeah, it's old-school ATX auxiliary power.

There should be plenty of good AT PSUs to be had on eBay though. Some are professionally refurbished and should be as good as new, and some even sell new old stock. I suppose it's worth keeping in mind that old caps may have dried up over the years and such, but in all honestly, I never saw an AT PSU fail back in the days (probably because they were a good bit simpler than ATX ones) but I've seen many cheap ATX ones fail over the years (only one of the ones I've had though and that was due to fan failure). Generally it seems like older electronics was more durable than newer. That being said, any and all old PC components are constantly at risk of sudden failure, and there's really no absolute way to avoid that. So all we can do is make the best build possible and hope it lasts a long time 😀

I have an AMD DX4/100 and a Cyrix 586. Which CPU will be suprior to the other ?

Pentium.

Er, I mean have you read feipoa's stickified thread?
The Ultimate 486 Benchmark Comparison

I say stick with the AMD classic 486

LunarG wrote:

That being said, any and all old PC components are constantly at risk of sudden failure, and there's really no absolute way to avoid that.

True, but it's always possible to maximize components life by reduicing heat with a good airflow and a decent cooling system, using branded PSU's supplying stable voltages equiped with decent capacitors, and last regularly clean dust 😀
Having components dying suddenly is rarer than just some bad contacts or similar issues (that can frequently appear with simm 72, simm 30 and DIP for example) .

Allright Folks. I can make it boot but I have to kick it a couple of times.

I have two PCI video card : ATI All-in Wonder and a CirrusLogic based card made by ATI.

I seem to have a problem with the PCI bus or the videocards. The cirruslogic card does not get detected all the time. The All-in Wonder is defective and will get detected but the video output is all messed-up. I do not have other video cards to try.

The only way I found to have successfull boot is by putting both videocard in it, but I need to jump a jumper on the All-in Wonder, otherwise nothing happens.

My 2x8MB ram gets detected as 8MB sometimes. Pretty sure this is bad contact.

I got 256kb cache and configured it for my AMD DX4-100 for the time being.
I have my IDE to SATA adapter. My floppy seems to be defective though.
I have a CDROM drive that should be working.

Right now, I think I need a PCI video card that is known to work in this computer.

486s won't boot from cdrom so you will want to get a working FDD
Make sure the cable is the right way round and its configured in the BIOS

As for the video card, I went through this same decision process. I settled on an S3 Virge but pretty much any older PCI card should wrok

smeezekitty wrote:

486s won't boot from cdrom so you will want to get a working FDD

Or better yet a USB floppy disk emulator so you don't have to deal with your 1.44MB floppies crapping out.

Artex wrote:

smeezekitty wrote:

486s won't boot from cdrom so you will want to get a working FDD

Or better yet a USB floppy disk emulator so you don't have to deal with your 1.44MB floppies crapping out.

How can I use that emulator to boot ? ?

Obligatory pictures :

Boot Video
http://youtu.be/28R3-vWDLFo

Easy peasy!

https://www.youtube.com/watch?v=dEjjGHv6860

I have floppy issue. I tested my current floppy drive on another system (floppy + cable) and it works.

On the 486 however, it doesn't.

I don't have any error message.
Floppy does not seek at boot even if specified in bios.
Swapped it for the B drive, same thing.

[EDIT 1]
I reset the bios using the jumper, and now I get the "Floppy Disk(s) fails (C0)" message.

[EDIT 2]
I even flashed Feopia's modified bios (using my programmer) and I get the same C0 error. Do I have a busted FDD controller ?

[EDIT 3]

Maybe I have an IDEA... There is this component, near the UM8663AF chip on the edge of the MOBO. This chip seem sto be the ISA controller chip (IDE + FLOPPY). The component I busted is identified as CB18. I replaced it with another component form another PCB, but it was identified as BC, not CB.

I do not know what type of component this CB18 is, but it could be a Circuit Breaker, as per many google search I did. If that's the case, I could replace it with a jumper wire.

Allright, my friend dropped me his box of old hardware... OMGWTFBBQ !! (I put an IO controller and disabled everything except the FDD controller, so I can now boot my biostar).

There is enough stuff to build like 6 complete systems in his box ! 286,386,486,socket 7, lots of VLB cards, vlb controller with cache on them (2).

i'm building another 486 based on the VL/I-486SV2GX4 !!! I'll

Synoptic wrote:

i'm building another 486 based on the VL/I-486SV2GX4 !!! I'll

That moment when you're so excited you don't even bother to finish your sentence. 🤣

Well, congrats! I guess you were going to say "I'll make a new thread" or something like that? 😁

archsan wrote:

Synoptic wrote:

i'm building another 486 based on the VL/I-486SV2GX4 !!! I'll

That moment when you're so excited you don't even bother to finish your sentence. 🤣

Well, congrats! I guess you were going to say "I'll make a new thread" or something like that? 😁

Ahaha, yeah !

I'll take pics too ! There is TON of HW to play with, I'm shaking !

You just need another AT style PSU, or buy an ATX to AT PSU cable instead.