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The perfect 486 motherboard

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First post, by aries-mu

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Hi guys, assuming you could order a custom, modern-made 486 motherboard, what specs would you request?

Here's what would be my request:

• Socket 2 and 3 compatible of course, compatible also with Pentium Overdrive
• Replaceable real 5ns L2 cache, min 512 KB, max 2048 KB (with modern manufacturing technologies I guess 5ns would be possible), fully stable @ 66 MHz with zero wait states
• 8x 72pin DIMM RAM slots (with custom ad-hoc 40ns FPM RAM modules also purchaseable, fully stable @ 66 MHz with zero wait states)
• Fully stable FSB @ 66 MHz
• CPU multiplier ON/OFF jumper
• Fully settable FSB: 16, 20, 25, 33, 40, 50, 60, and 66 MHz
• 66 MHz PCI 2.1 (backwards compatible) x4 slots
• Fully settable PCI slots via jumper: 16, 20, 25, 33, 40, 50, 60, and 66 MHz
• 3 EISA slots (ISA compatible), that, besides the default 8.3 MHz setting, can be forced to run also @ 12 MHz and 16 MHz
• 32 bit 66 MHz local-bus built-in caching Controller with 2x IDE PORTS, EIDE (PIO Modes up to 4) and UATA (up to UATA 133) compatible, with zero to 8 MB RAM using the same DIMMs as above for the main System RAM
• 32 bit 66 MHz local-bus built-in U2W SCSI Caching Controller (80 MB/sec) with two ports, with zero to 8 MB RAM using the same DIMMs as above for the main System RAM
EDIT: • Equipped with also 2xIDE-to-SD Card (each dual channel, master/slave selectable) and 2xSCSI-to-CF Card converters, full speed (able to use up the entire UATA for the first and U2W SCSI for the second bandwidths)
EDIT: • Dual Floppy Disk Drive port, up to 2x3.5" FDD and 1x5.25" FDD
• 32 bit 66 MHz local-bus built-in Cirrus Logic GD5434 SVGA with 2 MB of I have no idea what kind of memory would be better (I guess 45 ns DRAM, right?), disableable via jumper if one wants to use different SVGA cards in the PCI slots

Anything else?

Question for the most skilled/experienced: do you think such a beauty beast would be manufacturable today with modern technologies and current infrastructures? Or would manufacturing companies have to re-invest lots of money to buy totally different kinds of equipment to build the above or similar to the above?

Any further improvement, feature, different opinion on the specs?

Thanks

Last edited by aries-mu on 2018-12-17, 16:46. Edited 2 times in total.

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Reply 2 of 22, by cyclone3d

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Why SCSI or EIDE for that matter?

Just have SATA 150 via a Promise SATA150 controller. It would have to have a BIOS that supports booting CDs from the Promise controller though. The add-in cards don't allow that.

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Reply 3 of 22, by aries-mu

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cyclone3d wrote:

Why SCSI or EIDE for that matter?

Just have SATA 150 via a Promise SATA150 controller. It would have to have a BIOS that supports booting CDs from the Promise controller though. The add-in cards don't allow that.

Well, because, since we're talking about making a brand new motherboard from scratch, why having to relay on add-ons? Let's just through a range of connections building them in!

Also, the reason why IDE and SCSI are multiple:
• Oldies' vintage "feeling"
• Wide range of compatibility with vintage parts, there's a lot of old stuff out there that could be connected
• I'm not sure if the built-in peripherals like controller(s) and SVGA would be "local-bus-ed" via a different "bus" or if they will have to share the same PCI bus. In the second case, not to saturate too much the PCI bus with SATA 150 stuff. That's also why I chose U2W SCSI rather than SCSI 160 or SCSI 320.

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Reply 4 of 22, by Intel486dx33

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aries-mu wrote:
Well, because, since we're talking about making a brand new motherboard from scratch, why having to relay on add-ons? Let's just […]
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cyclone3d wrote:

Why SCSI or EIDE for that matter?

Just have SATA 150 via a Promise SATA150 controller. It would have to have a BIOS that supports booting CDs from the Promise controller though. The add-in cards don't allow that.

Well, because, since we're talking about making a brand new motherboard from scratch, why having to relay on add-ons? Let's just through a range of connections building them in!

Also, the reason why IDE and SCSI are multiple:
• Oldies' vintage "feeling"
• Wide range of compatibility with vintage parts, there's a lot of old stuff out there that could be connected
• I'm not sure if the built-in peripherals like controller(s) and SVGA would be "local-bus-ed" via a different "bus" or if they will have to share the same PCI bus. In the second case, not to saturate too much the PCI bus with SATA 150 stuff. That's also why I chose U2W SCSI rather than SCSI 160 or SCSI 320.

You probably would not want a hard drive for that matter. Just add a CF card slot or onboard SSD chip.

Reply 5 of 22, by aries-mu

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Intel486dx33 wrote:

Personally, I don't like fooling around with old hardware.
I just use a 486 for old software NOT the hardware.

Yeah, mine would be mainly for hardware-passionate people, but I wouldn't exclude it's convenient also for people focused only on using old software: the reliability of a modern-built motherboard is fantastic. They would just need to find an old CPU online, hook a monitor, keyboard, mouse, and you're all set! Well, the case+psu of course

Intel486dx33 wrote:

You probably would not want a hard drive for that matter. Just add a CF card slot or onboard SSD chip

Thanks bro, yeah see edits. I wouldn't like the "chip" onboard as I like replaceability for reliability/long term use purposes. Oh do you think one can add slots directly on the mobo? I had EDITED the thread adding IDE and SCSI to SD/CF converters...

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Reply 7 of 22, by aries-mu

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Intel486dx33 wrote:

There are CF card adapters that you plug directly into an IDE motherboard connector.

Right!

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Reply 8 of 22, by Koltoroc

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aries-mu wrote:

Hi guys, assuming you could order a custom, modern-made 486 motherboard, what specs would you request?

getting rid of most old standards. It doesn't matter how good that little experiment would be if the ecosystem to run it with isn't there

aries-mu wrote:

• Socket 2 and 3 compatible of course, compatible also with Pentium Overdrive

goes with the territory.

aries-mu wrote:

• Replaceable real 5ns L2 cache, min 512 KB, max 2048 KB (with modern manufacturing technologies I guess 5ns would be possible), fully stable @ 66 MHz with zero wait states

just put a few MB directly on die on the chipset and avoid the issue alltogether

aries-mu wrote:

• 8x 72pin DIMM RAM slots (with custom ad-hoc 40ns FPM RAM modules also purchaseable, fully stable @ 66 MHz with zero wait states)

Since you need a memory controller either way, just integrate a DDR2/3/4 controller and have easy access to cheap modern memory. Chances are that would be fast enough for cache not to matter at all.

aries-mu wrote:

• Fully stable FSB @ 66 MHz

sure, why not. The rest of the system would run asynchronous anyway because we can design it in a sane way to avoid stability issues.

aries-mu wrote:

• CPU multiplier ON/OFF jumper

sure, why not. BUT not all 486 even have selectable multipliers. Especially many DX/2 are hardwired.

aries-mu wrote:

• Fully settable FSB: 16, 20, 25, 33, 40, 50, 60, and 66 MHz

sure why not.

aries-mu wrote:

• 66 MHz PCI 2.1 (backwards compatible) x4 slots

no point, there is barely any hardware that supports that anyway.

aries-mu wrote:

• Fully settable PCI slots via jumper: 16, 20, 25, 33, 40, 50, 60, and 66 MHz

no. If we freshly design it we are keeping it sane and within specs. fixed 33Mhz or 66Mhz according to specs. Stability is key here.

aries-mu wrote:

• 3 EISA slots (ISA compatible), that, besides the default 8.3 MHz setting, can be forced to run also @ 12 MHz and 16 MHz

can do, but why? PCI already has anything you will ever need with the exception of soundcards and for that you only need ISA with chipset support for proper DMA/IRQ handling. EISA does nothing worthwhile on top of that that wouldn't be handled better by PCI cards.

aries-mu wrote:

• 32 bit 66 MHz local-bus built-in caching Controller with 2x IDE PORTS, EIDE (PIO Modes up to 4) and UATA (up to UATA 133) compatible, with zero to 8 MB RAM using the same DIMMs as above for the main System RAM

why? simple SATA ports will be easier to deal with and assuming you use an SSD the caching would do jack shit anyway. No point in going the IDE route. If for some godforsaken reason you absolutely HAVE to use an IDE device, just get an IDE to SATA adapter and be done with it.

aries-mu wrote:

• 32 bit 66 MHz local-bus built-in U2W SCSI Caching Controller (80 MB/sec) with two ports, with zero to 8 MB RAM using the same DIMMs as above for the main System RAM

that one makes slightly more sense, but only as an external port. There was a lot of peripheral gear that used SCSI. but for internal use what is the point? SATA will be faster and you can actually get new hardware for that. And if you insist on having the modern SCSI equivalent implement a SAS controler instead of SATA. It will be more expensive, but SATA devices will also work on it so outside of cost it wouldn't even be much of a downside. But since it is for a 486 the question again would be why.

aries-mu wrote:

EDIT: • Equipped with also 2xIDE-to-SD Card and 2xSCSI-to-CF Card converters, full speed (able to use up the entire UATA for the first and U2W SCSI for the second bandwidths)

sure could do, but why? You can already have SATA so not much of a point.

aries-mu wrote:

EDIT: • Dual Floppy Disk Drive port, up to 2x3.5" FDD and 1x5.25" FDD

missing a trick here, built in FDD emulator would be a good idea. but generally, it makes sense

aries-mu wrote:

• 32 bit 66 MHz local-bus built-in Cirrus Logic GD5434 SVGA with 2 MB of I have no idea what kind of memory would be better (I guess 45 ns DRAM, right?), disableable via jumper if one wants to use different SVGA cards in the PCI slots

good luck even getting such old video chips. How about instead we get some more modern integrated GPU instead? just make sure that the bios has proper VESA modes implemented. Also has the advantage that it could have HDMI output natively. Ideally with scaling, but that might be iffy.

aries-mu wrote:

Anything else?

-dedicated USB ports for mouse and keyboard that convert to PS/2 or with a bios implementation that has proper "legacy support" for them. It is getting harder to find good PS/2 mice and keyboards.
-PCIe x16 slot for a video card. The actual lane number doesn't matter just to have the option to use a video card with modern outputs (HDMI, Displayport) to avoid analogue to digital converter boxes

Most options should be configurable over the bios including some additional ones like actually available memory in case there are issues with too much memory. Various forms of "emulation" and legacy support in general, basically software defining most aspects of the system.

Maybe get the bios to support Nvme in a way that dos sees Nvme drives as regular fixed disks, not sure about the feasibility here.

I'm sure I can come up with more but that is enough for now.

aries-mu wrote:

Question for the most skilled/experienced: do you think such a beauty beast would be manufacturable today with modern technologies and current infrastructures? Or would manufacturing companies have to re-invest lots of money to buy totally different kinds of equipment to build the above or similar to the above?

could it be done? yes. However designing the hardware and manufacturing the components would be prohibitively expensive if you break it down to the few maniacs that would actually want to buy such a thing. It would just be not worth it. I know I wouldn't want to buy such a device at the prices you would have to ask for. It would make ebay prices look like the bargain of a century. A more sane approach would be to go the FPGA route like what is being done for old consoles (Retro AVS, Analogue NT mini, SuperNT, MegaSG) or homecomputers like Atari and Amiga (MiSTer) and completely emulate the entire hardware that way.

Making new 486 boards is an idea that pops every few months and it is just an unrealistic pipe dream. Many of the components needed have been out of production for decades and designing and manufacturing new chipsets is not going to happen for the lack of a market. And don't even bring up the argument that people already make new soundcards and midi interfaces. Those projects are orders of magnitudes simpler both on the PCB front as well as the ability to source parts since most cards use simple standard components anyway. A motherboard is a completely different beast.

Reply 9 of 22, by aries-mu

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Koltoroc wrote:

[...] Making new 486 boards is an idea that pops every few months and it is just an unrealistic pipe dream. Many of the components needed have been out of production for decades and designing and manufacturing new chipsets is not going to happen for the lack of a market. And don't even bring up the argument that people already make new soundcards and midi interfaces. Those projects are orders of magnitudes simpler both on the PCB front as well as the ability to source parts since most cards use simple standard components anyway. A motherboard is a completely different beast.

Wow, man! You definitely know your feces!

Well, you know what? Then, let's change project. Let's manufacture a time-machine and go back to the late nineties to "grab" stuff piled in warehouses before it gets scrapped, and then let's run away back in our present time... I guess it would be easier than manufacture new 486 motherboards like that 🤣
What about that? 🤣

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Reply 10 of 22, by cyclone3d

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aries-mu wrote:
Well, because, since we're talking about making a brand new motherboard from scratch, why having to relay on add-ons? Let's just […]
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cyclone3d wrote:

Why SCSI or EIDE for that matter?

Just have SATA 150 via a Promise SATA150 controller. It would have to have a BIOS that supports booting CDs from the Promise controller though. The add-in cards don't allow that.

Well, because, since we're talking about making a brand new motherboard from scratch, why having to relay on add-ons? Let's just through a range of connections building them in!

Also, the reason why IDE and SCSI are multiple:
• Oldies' vintage "feeling"
• Wide range of compatibility with vintage parts, there's a lot of old stuff out there that could be connected
• I'm not sure if the built-in peripherals like controller(s) and SVGA would be "local-bus-ed" via a different "bus" or if they will have to share the same PCI bus. In the second case, not to saturate too much the PCI bus with SATA 150 stuff. That's also why I chose U2W SCSI rather than SCSI 160 or SCSI 320.

So then have a PCI-e controller with PCI-e lanes for the data storage. If it would be a new chipset, then it shouldn't be too impossible to add that functionality.

I wasn't talking about having to have an add-in SATA controller. It would be onboard.

And if you wanted to use existing storage controllers that only support PCI, then you could even go as far as using a PCI-e <-> PCI bridge chip. The same chip even supports 66Mhz PCI.

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Reply 12 of 22, by Intel486dx33

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The perfect 486 motherboard would probably have fixed components.

Like

486dx4-133 with a bios CPU config soft menu for changing the speed of the CPU with-in the bios.
Onboard 32mb ram
Onboard 512kb Cache.
Onboard 540mb SSD.
Onboard SVGA
Onboard Sound chip.
Onboard Network chip.
Onboard Wireless networking
Wireless keyboard and mouse.
Built in Powersupply with PSU
Built-in USB, floppy, cdrom, scsi port.
In a ultra small form factor case.
Nice display

Probably a 486 laptop form factor.

Reply 13 of 22, by aries-mu

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Intel486dx33 wrote:
The perfect 486 motherboard would probably have fixed components. […]
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The perfect 486 motherboard would probably have fixed components.

Like

486dx4-133 with a bios CPU config soft menu for changing the speed of the CPU with-in the bios.
Onboard 32mb ram
Onboard 512kb Cache.
Onboard 540mb SSD.
Onboard SVGA
Onboard Sound chip.
Onboard Network chip.
Onboard Wireless networking
Wireless keyboard and mouse.
Built in Powersupply with PSU
Built-in USB, floppy, cdrom, scsi port.
In a ultra small form factor case.
Nice display

Probably a 486 laptop form factor.

You present good points from an exclusively practical/utilitaristic point of view. Like if you "need" the platform to run something you need to run.
On the other hand, for all the vintage/retro 90s enthusiasts, it would have no use, because, for example:
• no legendary huge beige desktop/midtower case
• no customization/replaceability/tweaking possibilities for CPU, cards, etc.
• no use to let other old parts work again

Again, let's go with the time-machine, raid old-stock semi-abandoned warehouse in the late 90s, and run back in our present 🤣

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Reply 14 of 22, by aries-mu

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Koltoroc wrote:
aries-mu wrote:

• 66 MHz PCI 2.1 (backwards compatible) x4 slots

no point, there is barely any hardware that supports that anyway.

For the sake of stability with broad-range of CPUs and possible CPU/FSB overclocking fun activities (provided the right SVGA cards will be chosen). Even without going the overclock way, even simple 486 CPUs like the DX40, DX2-80, and DX4-120, with an FSB set at 40 MHz, most of the times had to downclock the PCI bus at a ridiculous 27 MHz, just because it wouldn't even be stable at 40 instead of 33. Not talking about the stability with FSBs at 50 and 66 MHz. That would solve all the issues.

Koltoroc wrote:
aries-mu wrote:

• 3 EISA slots (ISA compatible), that, besides the default 8.3 MHz setting, can be forced to run also @ 12 MHz and 16 MHz

can do, but why? PCI already has anything you will ever need with the exception of soundcards and for that you only need ISA with chipset support for proper DMA/IRQ handling. EISA does nothing worthwhile on top of that that wouldn't be handled better by PCI cards.

Well, to make it appealing to ALL and EVERY possible vintage-computing user.
You got an ISA card, which happens very commonly? It can run in an EISA slot.
You got a rare EISA card and would love to use it in your brand-new-motherboard vintage computer? You can't use it in an ISA slot, but you can in an EISA one.
So, since you're going to add an ISA chipset, it might as well be EISA, am I right?

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Reply 15 of 22, by skitters

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IMO the most important feature would be fine-grained control of processor speed that could be adjusted on the fly, without having to reboot to the BIOS to adjust cache. The motherboard should allow you to adjust speed-sensitive games like Wing Commander, where optimum processor speed varies with how many enemies are on screen.

The 2nd most important feature would be the ability to accept every piece of old hardware that I felt like putting into it, without any weird hardware conflicts. And it should be able to disable unwanted connectors on hardware, like LMSI connectors on certain sound cards, that do nothing useful (unless you have an extremely rare LMSI CD drive in working order) and often conflict with IDE ports.

Reply 16 of 22, by aries-mu

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skitters wrote:

IMO the most important feature would be fine-grained control of processor speed that could be adjusted on the fly, without having to reboot to the BIOS to adjust cache. The motherboard should allow you to adjust speed-sensitive games like Wing Commander, where optimum processor speed varies with how many enemies are on screen.

The 2nd most important feature would be the ability to accept every piece of old hardware that I felt like putting into it, without any weird hardware conflicts. And it should be able to disable unwanted connectors on hardware, like LMSI connectors on certain sound cards, that do nothing useful (unless you have an extremely rare LMSI CD drive in working order) and often conflict with IDE ports.

Definitely them all!!! Thanks! ↑↑↑↑↑

Except, for the Cache part, I totally agree with Koltoroc:

Koltoroc wrote:

Since you need a memory controller either way, just integrate a DDR2/3/4 controller and have easy access to cheap modern memory. Chances are that would be fast enough for cache not to matter at all.

Also, modern RAM should also withstand any possible 486 CPU frequency up to the most insane overclocking madnesses, like DX4 180 MHz or things like that 🤣, am I correct guys?

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Reply 17 of 22, by Baoran

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My perfect 486 would be:
ps/2 keyboard and mouse ports
Coin battery
256Kb of fast L2 cache
4 slots of 72 pin ram
3 VLB slots and 4 ISA slots
Turbo button function that cuts the cpu speed in half.
Fast bug free chipset.
Compatible with all 486 cpus with ZIF slot 3.
Integrated ide (with LBA), serial and parallel port headers.
No electrolytic capacitors that fail. (Or perhaps socketed ones that are easy to replace as often as you want without soldering)

Reply 18 of 22, by aries-mu

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Baoran wrote:
My perfect 486 would be: ps/2 keyboard and mouse ports Coin battery 256Kb of fast L2 cache 4 slots of 72 pin ram 3 VLB slots an […]
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My perfect 486 would be:
ps/2 keyboard and mouse ports
Coin battery
256Kb of fast L2 cache
4 slots of 72 pin ram
3 VLB slots and 4 ISA slots
Turbo button function that cuts the cpu speed in half.
Fast bug free chipset.
Compatible with all 486 cpus with ZIF slot 3.
Integrated ide (with LBA), serial and parallel port headers.
No electrolytic capacitors that fail. (Or perhaps socketed ones that are easy to replace as often as you want without soldering)

Yeah great point the capacitors!!!! Right! Either socketed or solid.

Thanks

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Reply 19 of 22, by elod

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Socketed whaat? For a 486 SMD caps would be the simplest way to go. Way less layers than on modern boards.
Otherwise I completely agree with the previous poster who said that it's totally impractical to build something like this. A time machine project is more useful.

To me the perfect 486 would he a socket7 board.