Solve : 486 Board Compatibility?

1.	Solve : 486 Board Compatibility?
Answer» Are 486 boards compatibile with all 486 processors? No. There is none. Why do you need one? actually I need a socket 3 board and unfortunately, people selling mb's on ebay don't always know what socket their mother board is. I'm considering a board that has a DX4 processor and need to know if a DX2 processor will work on itHi A board that supports a DX4 CPU will support a DX2. To be sure perhaps post the motherboard you have and the one you intead to use to replace it, To confirm. Quote from: Lisa_maree on December 17, 2014, 12:24:42 PM Hi A board that supports a DX4 CPU will support a DX2. To be sure perhaps post the motherboard you have and the one you intead to use to replace it, To confirm. Thank you Lisa for that info I'm building an AT DOS 486DX2/66 gaming machine and in info/parts gathering mode I do have another question. I would like to have between 128k and 256k of L2 cache on the motherboard. If I cant find one that has it, is it possible to add that to the motherboard? I assume the way to check L2 cache on the motherboard is in the bios, right?Some of the later model 486 boards had a Cache slot available to add a Cache module. This did not become popular though until the Pentium's came out with the newer socket. Here is a motherboard that I do not suggest buying because its not universal and lacking PCI slots etc, but has a 256k Cache module. They are out there, you just need to find one that matches all specs you have. This is an already working board with CPU, Cache, and RAM. http://www.ebay.com/itm/Gateway-09-00144-01-486-DX2-66MHz-16MB-RAM-Baby-AT-Motherboard-w-VLB-Slots-/311190503432?pt=US_Vintage_Computing_Parts_Accessories&hash=item4874664008 For how cheap a 486 motherboard is with processor and RAM included, you might as well go with a known good combination VS buying a motherboard without a CPU already stuffed into it. If a board is being sold without the CPU, then someone has PRIED the CPU out of it. If they claim its a working board but no CPU included then they still pried the CPU out of it. I'd avoid buying a bare used board that doesnt come with a CPU already in it. Some other things to consider when buying a motherboard of the 486 era: Do you want a motherboard that has the Socket 3 which is press fit CPU into socket or the more modern eject lever? Do you need any PCI slots or just ISA 8 and 16 bit slots? Do you need PS2 ports for Mouse/Keyboard or are you going to go with a larger AT keyboard and a 9-pin serial mouse? Are you looking for a universal AT type board or a specialty board for the case you are using? Do you require any VESA slots? Most 486 era motherboard CMOS batteries are BAD and most are leaking or have already leaked onto the motherboard, are you prepared to have to replace this battery without killing the main board? (* Years ago I had to fix a board that the acid leaked out of the battery and ate the traces off of the top of the board through the mask, and instead of placing the same battery back into it, i had a 2 x AA Radio Shack battery cradle and so I wired that up for my 3 volts to hold the system time and BIOS config info. ) Do you have an older power supply with the P8 and P9 connectors to it? ---------------------------------------------------------------- Lastly you might find it cheaper to buy a whole computer already assembled and working vs assembling a 486 system piece by piece!!!No pci slots needed, I don't think they exist on 486 boards, at least not on the dozens of them I've seen in the past. I didn't know they pressed those processors into the boards back then, thx for that info. Basicly I'm looking for an AT form factor Socket 3 motherboard, 256k L2 cache on board, 486DX2/66 processor, 2-3 VLB slots and 4 or more 16bit ISA slots. I've got a Buslogic SCSI card that will fit into a VLB slot (which is about equal in speed to pci) which will take larger hard drives than the IDE with room to connect 7 devices. I can get a PS2 adapter for the keyboard but will probably have to use a serial mouse (both available online). I'm getting a new big AT case on Amazon. I plan on replacing the CMOS battery with an external one that plugs into the motherboard. I've NEVER done one of these old boards before. This board has more connection options http://www.ebay.com/itm/131376307288?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT It also has a lockdown lever for the processor (which I already have). Only thing is it doesn't have regular P8, P9 power connections. hmmm I know it's going to cost more this way but half of the fun for me is building and customizing. 486 systems were typically PCI/ISA about halfway through their lifespan. In particular 486 boards that supported a Pentium overdrive pretty much always had PCI/ISA. I've never seen an ISA only 486 board myself- usually it is either PCI/ISA or VL-Bus/ISA. the 486 CPUs used Socket 3 (as you've mentioned), which was Zero-Insertion Force. Cheaper motherboards didn't use the standard Socket 3 and instead used a modified version which was Low-Insertion Force. I've never seen them myself, though. Typically removing a CPU was as one would expect- you lift a lever and remove the CPU. Sometimes it was a plastic tab or small metal rod that you pulled SIDEWAYS, and personally my sample size is only one, but the 486 system I had previously used a ZIF socket and there was no requirement to "pry" out the CPU. I've never seen a header for an external CMOS battery, though I haven't looked for them. Every board I've had aside from a 286 which used a cigar-censored battery used a CR2032. This board linked here had the socket that required a special CPU removal tool that grabbed at the corners of the 486 or as i had to do back in the day.... carefully pry up each corner evenly with a small flat head screw driver until the CPU could be removed trying to avoid damaging pins, and then push the replacement CPU into the socket. The socket next to the CPU on this board was either a 487 math co-processor or overdrive socket. And the socket that the 486 is stuffed into is the same socket type on this board. It may be low insertion force, but most were pried up to get them out at their corners. I've been working on computers going back to the 1980s with 8086, 8088, 286, 386, and lots of 486's in the early 90s with the SX ( = s u c k s ) processor in which I was quite busy upgrading people, mostly gamers, to the DX processor for both the 386 and 486 systems. Many of the CPUs had to be pried up carefully at their corners although the 8086 and 8088's I never had to remove as for there was no drastic upgrade back then other than finding an 8087 if you could afford one and needed that complexity of math computed. http://www.ebay.com/itm/Gateway-09-00144-01-486-DX2-66MHz-16MB-RAM-Baby-AT-Motherboard-w-VLB-Slots-/311190503432?pt=US_Vintage_Computing_Parts_Accessories&hash=item4874664008That is for a pre-built OEM system, and I think it might be an earlier one, so it may also be a case of manufacturer's at the time adjusting to the newer, standardized ZIF sockets (as opposed to the 386 and earlier where you had surface mount and basically any mounting socket the manufacturer wanted). I believe the one I had, personally, was a later VIA motherboard, and it had on-board sound (if my memory serves- a, ESS audio drive). Mine was a very late model as I understand since it was a 120-Mhz DX4, enough to require a CPU Fan. I'm not sure what the upgrade CHIP could be. It's not a Overdrive slot since the overdrive had ~235 Pins, and that has 169. It might be that the motherboard was for a 486SX and thus supported a 487 (which would otherwise be built into a DX). Or perhaps a proprietary upgrade slot.

Answer»

Are 486 boards compatibile with all 486 processors? No. There is none.
Why do you need one?
actually I need a socket 3 board and unfortunately, people selling mb's on ebay don't always know what socket their mother board is. I'm considering a board that has a DX4 processor and need to know if a DX2 processor will work on itHi

A board that supports a DX4 CPU will support a DX2. To be sure perhaps post the motherboard you have and the one you intead to use to replace it, To confirm. Quote from: Lisa_maree on December 17, 2014, 12:24:42 PM

Hi

A board that supports a DX4 CPU will support a DX2. To be sure perhaps post the motherboard you have and the one you intead to use to replace it, To confirm.

Thank you Lisa for that info I'm building an AT DOS 486DX2/66 gaming machine and in info/parts gathering mode I do have another question. I would like to have between 128k and 256k of L2 cache on the motherboard. If I cant find one that has it, is it possible to add that to the motherboard?
I assume the way to check L2 cache on the motherboard is in the bios, right?Some of the later model 486 boards had a Cache slot available to add a Cache module. This did not become popular though until the Pentium's came out with the newer socket.

Here is a motherboard that I do not suggest buying because its not universal and lacking PCI slots etc, but has a 256k Cache module. They are out there, you just need to find one that matches all specs you have. This is an already working board with CPU, Cache, and RAM. http://www.ebay.com/itm/Gateway-09-00144-01-486-DX2-66MHz-16MB-RAM-Baby-AT-Motherboard-w-VLB-Slots-/311190503432?pt=US_Vintage_Computing_Parts_Accessories&hash=item4874664008

For how cheap a 486 motherboard is with processor and RAM included, you might as well go with a known good combination VS buying a motherboard without a CPU already stuffed into it. If a board is being sold without the CPU, then someone has PRIED the CPU out of it. If they claim its a working board but no CPU included then they still pried the CPU out of it.

I'd avoid buying a bare used board that doesnt come with a CPU already in it.

Some other things to consider when buying a motherboard of the 486 era:

Do you want a motherboard that has the Socket 3 which is press fit CPU into socket or the more modern eject lever?

Do you need any PCI slots or just ISA 8 and 16 bit slots?

Do you need PS2 ports for Mouse/Keyboard or are you going to go with a larger AT keyboard and a 9-pin serial mouse?

Are you looking for a universal AT type board or a specialty board for the case you are using?

Do you require any VESA slots?

Most 486 era motherboard CMOS batteries are BAD and most are leaking or have already leaked onto the motherboard, are you prepared to have to replace this battery without killing the main board?
(* Years ago I had to fix a board that the acid leaked out of the battery and ate the traces off of the top of the board through the mask, and instead of placing the same battery back into it, i had a 2 x AA Radio Shack battery cradle and so I wired that up for my 3 volts to hold the system time and BIOS config info. )

Do you have an older power supply with the P8 and P9 connectors to it?

----------------------------------------------------------------
Lastly you might find it cheaper to buy a whole computer already assembled and working vs assembling a 486 system piece by piece!!!No pci slots needed, I don't think they exist on 486 boards, at least not on the dozens of them I've seen in the past. I didn't know they pressed those processors into the boards back then, thx for that info. Basicly I'm looking for an AT form factor Socket 3 motherboard, 256k L2 cache on board, 486DX2/66 processor, 2-3 VLB slots and 4 or more 16bit ISA slots.

I've got a Buslogic SCSI card that will fit into a VLB slot (which is about equal in speed to pci) which will take larger hard drives than the IDE with room to connect 7 devices. I can get a PS2 adapter for the keyboard but will probably have to use a serial mouse (both available online).

I'm getting a new big AT case on Amazon. I plan on replacing the CMOS battery with an external one that plugs into the motherboard. I've NEVER done one of these old boards before.
This board has more connection options http://www.ebay.com/itm/131376307288?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT It also has a lockdown lever for the processor (which I already have). Only thing is it doesn't have regular P8, P9
power connections. hmmm

I know it's going to cost more this way but half of the fun for me is building and customizing. 486 systems were typically PCI/ISA about halfway through their lifespan. In particular 486 boards that supported a Pentium overdrive pretty much always had PCI/ISA. I've never seen an ISA only 486 board myself- usually it is either PCI/ISA or VL-Bus/ISA.

the 486 CPUs used Socket 3 (as you've mentioned), which was Zero-Insertion Force. Cheaper motherboards didn't use the standard Socket 3 and instead used a modified version which was Low-Insertion Force. I've never seen them myself, though. Typically removing a CPU was as one would expect- you lift a lever and remove the CPU. Sometimes it was a plastic tab or small metal rod that you pulled SIDEWAYS, and personally my sample size is only one, but the 486 system I had previously used a ZIF socket and there was no requirement to "pry" out the CPU.

I've never seen a header for an external CMOS battery, though I haven't looked for them. Every board I've had aside from a 286 which used a cigar-*censored* battery used a CR2032.
This board linked here had the socket that required a special CPU removal tool that grabbed at the corners of the 486 or as i had to do back in the day.... carefully pry up each corner evenly with a small flat head screw driver until the CPU could be removed trying to avoid damaging pins, and then push the replacement CPU into the socket. The socket next to the CPU on this board was either a 487 math co-processor or overdrive socket. And the socket that the 486 is stuffed into is the same socket type on this board. It may be low insertion force, but most were pried up to get them out at their corners.

I've been working on computers going back to the 1980s with 8086, 8088, 286, 386, and lots of 486's in the early 90s with the SX ( = s u c k s ) processor in which I was quite busy upgrading people, mostly gamers, to the DX processor for both the 386 and 486 systems. Many of the CPUs had to be pried up carefully at their corners although the 8086 and 8088's I never had to remove as for there was no drastic upgrade back then other than finding an 8087 if you could afford one and needed that complexity of math computed.

http://www.ebay.com/itm/Gateway-09-00144-01-486-DX2-66MHz-16MB-RAM-Baby-AT-Motherboard-w-VLB-Slots-/311190503432?pt=US_Vintage_Computing_Parts_Accessories&hash=item4874664008That is for a pre-built OEM system, and I think it might be an earlier one, so it may also be a case of manufacturer's at the time adjusting to the newer, standardized ZIF sockets (as opposed to the 386 and earlier where you had surface mount and basically any mounting socket the manufacturer wanted). I believe the one I had, personally, was a later VIA motherboard, and it had on-board sound (if my memory serves- a, ESS audio drive). Mine was a very late model as I understand since it was a 120-Mhz DX4, enough to require a CPU Fan.

I'm not sure what the upgrade CHIP could be. It's not a Overdrive slot since the overdrive had ~235 Pins, and that has 169. It might be that the motherboard was for a 486SX and thus supported a 487 (which would otherwise be built into a DX). Or perhaps a proprietary upgrade slot.

Solve : 486 Board Compatibility?

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