You don't mention whether your current board (and the expansion cards you want to use) is PCI or VLB. That will be biggest decision on the board. Only a handful of boards handle EDO. Those tend to be PCI. A late PCI board and only a 486DX2/66 would be a little oddball of a combination, I feel like a DX4 or Am5x86 would be more of a fit. I'm on the lookout for a good UM8881F board with PCI, PS/2 mouse and Award BIOS myself sometime.

External battery connectors are also good, especially if you're sure the board doesn't try to charge the external battery. Digi-Key sells a 3xAA battery holder with the wires already attached and the connector keyed the correct way for the missing pin on the board.

No reason not to use DOS 6.22 on a 486. Some like to use "back-ported" versions of DOS that have been extracted from Windows 98SE but on only a 500MB drive plain old FAT16+DOS 6.22 will be fine.

5.25" floppy size only matters if you actually want to write disks readable on another machine. When 1.2MB drives write to 360KB disks it doesn't turn out well, something about track width, and they tend not to be readable afterward on a 360KB drive.

It would be good to post two pictures of your board, one overall and two for the battery area (top and bottom). There are good hardware people on here who will assess the damage.

jakethompson1 wrote on 2020-08-02, 22:03:

You don't mention whether your current board (and the expansion cards you want to use) is PCI or VLB. That will be biggest decis […]
Show full quote

You don't mention whether your current board (and the expansion cards you want to use) is PCI or VLB. That will be biggest decision on the board. Only a handful of boards handle EDO. Those tend to be PCI. A late PCI board and only a 486DX2/66 would be a little oddball of a combination, I feel like a DX4 or Am5x86 would be more of a fit. I'm on the lookout for a good UM8881F board with PCI, PS/2 mouse and Award BIOS myself sometime.

External battery connectors are also good, especially if you're sure the board doesn't try to charge the external battery. Digi-Key sells a 3xAA battery holder with the wires already attached and the connector keyed the correct way for the missing pin on the board.

No reason not to use DOS 6.22 on a 486. Some like to use "back-ported" versions of DOS that have been extracted from Windows 98SE but on only a 500MB drive plain old FAT16+DOS 6.22 will be fine.

5.25" floppy size only matters if you actually want to write disks readable on another machine. When 1.2MB drives write to 360KB disks it doesn't turn out well, something about track width, and they tend not to be readable afterward on a 360KB drive.

It would be good to post two pictures of your board, one overall and two for the battery area (top and bottom). There are good hardware people on here who will assess the damage.

Thank you I have updated the original post and here are the pic of current mobo that doesn't boot or post and it is a socket 3

Bummer ! You do have some major corrosion, those coin cells could do as much as the barrel batteries. That should actually not stop it from at least bootin to a bios screen but then again I also see a major scratch on one of the IC's. Ok off the top of my head would look for a 486 w/PCI board to match up, FIC-486PIO2, Giga GA486IM, Asus 486SP3G etc. There are a few but not sure which would be best and none will be cheap.

Horun wrote on 2020-08-03, 02:31:

Bummer ! You do have some major corrosion, those coin cells could do as much as the barrel batteries. That should actually not stop it from at least bootin to a bios screen but then again I also see a major scratch on one of the IC's. Ok off the top of my head would look for a 486 w/PCI board to match up, FIC-486PIO2, Giga GA486IM, Asus 486SP3G etc. There are a few but not sure which would be best and none will be cheap.

Thank you and where is the scratch on the ic

Robhalfordfan wrote on 2020-08-03, 07:24:

[...]

Thank you and where is the scratch on the ic

Right-hand Winbond chip, between top PCI slot and SIMMs.

Abit PB4 is another motherboard to add to the search list but as already mentioned 486 motherboards are rare and overpriced.
You've already given yourself a good goal that narrows your search (socket 3, PCI, No barrel or Dallas battery) I'd jump on anything that matches that criteria for a good price.

dionb wrote on 2020-08-03, 07:39:

Robhalfordfan wrote on 2020-08-03, 07:24:

[...]

Thank you and where is the scratch on the ic

Right-hand Winbond chip, between top PCI slot and SIMMs.

ohh i did see it wasnt a scratch - it dried up hot glue as i discovered the was a loads of hot glue blobs and pull off as much as possible

would it be possible to solder a coin cell battery holder where the old barrel battery was originally or will i need something else for that to work or better to find a motherboard replacement

chinny22 wrote on 2020-08-03, 08:40:

Abit PB4 is another motherboard to add to the search list but as already mentioned 486 motherboards are rare and overpriced.
You've already given yourself a good goal that narrows your search (socket 3, PCI, No barrel or Dallas battery) I'd jump on anything that matches that criteria for a good price.

yeah and what would be a good price and if there is any other ideas and/or add-ons (eg - cards, hdd etc) to make it a close to period accurate as possible

i have updated the first post saying that i am open the idea of ISA/VLB as along as it use coin battery whichever is easier to find and get for a good price

Robhalfordfan wrote on 2020-08-03, 11:26:

[...]

ohh i did see it wasnt a scratch - it dried up hot glue as i discovered the was a loads of hot glue blobs and pull off as much as possible

would it be possible to solder a coin cell battery holder where the old barrel battery was originally or will i need something else for that to work or better to find a motherboard replacement

Physically: certainly. Electrically: some boards need 3.6V and lose CMOS settings with 3.3V. Also consider that the old battery was rechargeable. Two options: add a diode to allow you to use CR-2032 (and lose a bit more voltage) or add a coin cell holder but use a LIR-2032 rechargeable coin.

dionb wrote on 2020-08-04, 06:19:

Robhalfordfan wrote on 2020-08-03, 11:26:

[...]

ohh i did see it wasnt a scratch - it dried up hot glue as i discovered the was a loads of hot glue blobs and pull off as much as possible

would it be possible to solder a coin cell battery holder where the old barrel battery was originally or will i need something else for that to work or better to find a motherboard replacement

Physically: certainly. Electrically: some boards need 3.6V and lose CMOS settings with 3.3V. Also consider that the old battery was rechargeable. Two options: add a diode to allow you to use CR-2032 (and lose a bit more voltage) or add a coin cell holder but use a LIR-2032 rechargeable coin.

Ok so is there already pre made things made or is it easier just find another socket 3 board that already has coin cell battery on it already

Robhalfordfan wrote on 2020-08-04, 07:57:

dionb wrote on 2020-08-04, 06:19:

Robhalfordfan wrote on 2020-08-03, 11:26:

[...]

ohh i did see it wasnt a scratch - it dried up hot glue as i discovered the was a loads of hot glue blobs and pull off as much as possible

would it be possible to solder a coin cell battery holder where the old barrel battery was originally or will i need something else for that to work or better to find a motherboard replacement

Physically: certainly. Electrically: some boards need 3.6V and lose CMOS settings with 3.3V. Also consider that the old battery was rechargeable. Two options: add a diode to allow you to use CR-2032 (and lose a bit more voltage) or add a coin cell holder but use a LIR-2032 rechargeable coin.

Ok so is there already pre made things made or is it easier just find another socket 3 board that already has coin cell battery on it already

Yes, 2032 coin cell holders are entirely standard and can be bought at just about any electronics outlet. The only difference between CR-2032 and LIR-2032 is the internal chemistry of the battery. This board looks prepared for one in any case, the big circle around the battery looks suspiciously like a coin cell holder outline.

dionb wrote on 2020-08-04, 09:25:

Robhalfordfan wrote on 2020-08-04, 07:57:

dionb wrote on 2020-08-04, 06:19:

Physically: certainly. Electrically: some boards need 3.6V and lose CMOS settings with 3.3V. Also consider that the old battery was rechargeable. Two options: add a diode to allow you to use CR-2032 (and lose a bit more voltage) or add a coin cell holder but use a LIR-2032 rechargeable coin.

Ok so is there already pre made things made or is it easier just find another socket 3 board that already has coin cell battery on it already

Yes, 2032 coin cell holders are entirely standard and can be bought at just about any electronics outlet. The only difference between CR-2032 and LIR-2032 is the internal chemistry of the battery. This board looks prepared for one in any case, the big circle around the battery looks suspiciously like a coin cell holder outline.

i manage to find the manual and accordingto it, the battery used 3.6v/480mA LI battery

i since it cheap (most likely) to get coin batterys and holder and i own a soldering iron and have an idea thinking it might not boot or post because it missing a battery (doubt it - no harm in trying)

ram - edo ram (various sizes)

There's a chance your motherboard will only accept FPM RAM, or that the RAM you have is FPM instead of EDO. The difference between them can be hard to tell. There are some topics about it here on Vogons if you're interested. They can explain it better than I can.

But if the system doesn't POST or give "no RAM" beeps, that might be the cause.

HandOfFate wrote on 2020-08-04, 10:13:

ram - edo ram (various sizes)

There's a chance your motherboard will only accept FPM RAM, or that the RAM you have is FPM instead of EDO. The difference between them can be hard to tell. There are some topics about it here on Vogons if you're interested. They can explain it better than I can.

But if the system doesn't POST or give "no RAM" beeps, that might be the cause.

thats that i own but not sure what ram came with computer and been using that as they look the same as edo ram, so i just assumed

the ram the came with computer both have chips which all say toshiba TC514400ASJ-70 and the chips are on one side only

doesn't post or beep with the ram that was already there

Good catch!
Going off this table
https://en.wikipedia.org/wiki/ALi_Corporation#80X86_Chipsets
and that you have M1445 south bridge and PCI think its a safe bet its the M1439 M/B which doesn't take EDO
Sadly TC514400ASJ-70 looks to be FPM so were still no better off though.

As your open to basically anything that doesn't have onboard battery OEM system maybe good option as they go for a bit less. Usually the M/B and case aren't standard but everything else including the PSU are all generic.
But what's a fair price will depend on you. I got a complete system off freecycle last week and that was me replying to a post for Amstrad computers. I wasn't actually looking for another 486 at all!

chinny22 wrote on 2020-08-04, 10:40:

Good catch! Going off this table https://en.wikipedia.org/wiki/ALi_Corporation#80X86_Chipsets and that you have M1445 south br […]
Show full quote

Good catch!
Going off this table
https://en.wikipedia.org/wiki/ALi_Corporation#80X86_Chipsets
and that you have M1445 south bridge and PCI think its a safe bet its the M1439 M/B which doesn't take EDO
Sadly TC514400ASJ-70 looks to be FPM so were still no better off though.

As your open to basically anything that doesn't have onboard battery OEM system maybe good option as they go for a bit less. Usually the M/B and case aren't standard but everything else including the PSU are all generic.
But what's a fair price will depend on you. I got a complete system off freecycle last week and that was me replying to a post for Amstrad computers. I wasn't actually looking for another 486 at all!

ok learn something new everyday - never heard of fpm ram and basically just mobo that accpets dx2 66 and use a coin battery instead of barrel battery

pci and isa is prob easier as i few different cards and do not own any vlb cards at all and if comes with ram thats fine but i said i have fair few stick of edo ram

i have also posted on amibay (which i got older retro parts from there in past no problem before)

been looking at socket 3 mobos and wondering if any of these would work best for a 486dx2 - with a little bit of expand ably/upgrading etc

some i think i found manuals for some but not all of them and if anyone has or know where to find the manuals, would be greatly appreciated

i am aware of prices and try to narrow down at least and get a better idea and what would work best

https://www.ebay.co.uk/itm/ACORP-486-PCI-moth … M-/324267798436
https://www.ebay.co.uk/itm/ASUS-PVI-486SP3-RE … AT/324249571030
https://www.ebay.co.uk/itm/486-SOCKET-2-AT-Ma … le/224007973202
https://www.ebay.co.uk/itm/SMT-486-5x86-Termi … -8/224130473356
https://www.ebay.co.uk/itm/ATC-1415-motherboa … ng/224054065314

Robhalfordfan wrote on 2020-08-29, 17:04:

been looking at socket 3 mobos and wondering if any of these would work best for a 486dx2 - with a little bit of expand ably/upg […]
Show full quote

been looking at socket 3 mobos and wondering if any of these would work best for a 486dx2 - with a little bit of expand ably/upgrading etc

some i think i found manuals for some but not all of them and if anyone has or know where to find the manuals, would be greatly appreciated

i am aware of prices and try to narrow down at least and get a better idea and what would work best

https://www.ebay.co.uk/itm/ACORP-486-PCI-moth … M-/324267798436
https://www.ebay.co.uk/itm/ASUS-PVI-486SP3-RE … AT/324249571030
https://www.ebay.co.uk/itm/486-SOCKET-2-AT-Ma … le/224007973202
https://www.ebay.co.uk/itm/SMT-486-5x86-Termi … -8/224130473356
https://www.ebay.co.uk/itm/ATC-1415-motherboa … ng/224054065314

I assume you know about "Total Hardware 1999" (search for it) already which may help with the info you'd need from the manual.
A 486DX2 is pretty universally compatible. I would personally go for the ATC-1415 for the UMC chipset. It looks like each board has 256KB cache so they should be fairly equivalent especially since you're only running 33MHz bus. The ASUS appears to have 8 32-pin cache sockets so it may be expandable to more cache than the others, if you plan on using more than 32MB RAM.

I wouldn't consider the DX2-80 included with one of those boards to be a bonus really. Running a PCI board at 40MHz is problematic because PCI (which is supposed to be 33 MHz) is either overclocked at 40, or under-clocked at 2/3 * 40.

jakethompson1 wrote on 2020-08-29, 18:40:

I assume you know about "Total Hardware 1999" (search for it) already which may help with the info you'd need from the manual. A […]
Show full quote

Robhalfordfan wrote on 2020-08-29, 17:04:

been looking at socket 3 mobos and wondering if any of these would work best for a 486dx2 - with a little bit of expand ably/upg […]
Show full quote

been looking at socket 3 mobos and wondering if any of these would work best for a 486dx2 - with a little bit of expand ably/upgrading etc

some i think i found manuals for some but not all of them and if anyone has or know where to find the manuals, would be greatly appreciated

i am aware of prices and try to narrow down at least and get a better idea and what would work best

https://www.ebay.co.uk/itm/ACORP-486-PCI-moth … M-/324267798436
https://www.ebay.co.uk/itm/ASUS-PVI-486SP3-RE … AT/324249571030
https://www.ebay.co.uk/itm/486-SOCKET-2-AT-Ma … le/224007973202
https://www.ebay.co.uk/itm/SMT-486-5x86-Termi … -8/224130473356
https://www.ebay.co.uk/itm/ATC-1415-motherboa … ng/224054065314

I assume you know about "Total Hardware 1999" (search for it) already which may help with the info you'd need from the manual.
A 486DX2 is pretty universally compatible. I would personally go for the ATC-1415 for the UMC chipset. It looks like each board has 256KB cache so they should be fairly equivalent especially since you're only running 33MHz bus. The ASUS appears to have 8 32-pin cache sockets so it may be expandable to more cache than the others, if you plan on using more than 32MB RAM.

I wouldn't consider the DX2-80 included with one of those boards to be a bonus really. Running a PCI board at 40MHz is problematic because PCI (which is supposed to be 33 MHz) is either overclocked at 40, or under-clocked at 2/3 * 40.

thank you for website as i have never heard of it and have bookmarked it

would having more cache help in any way other than more ram higher than 32mb

would prob keep it dx2 - 66mhz for a while and use somewhere between 16-25mb ram and use edo ram (as i have loads of sticks)

thank you for your help as it is helping as i looking for a mobo that is maybe to the best of the best but somewhere between good enough and close too the best