You'll need an ISA floppy controller. They often also come with serial ports.

Yes of course, how stupid can I be… brain fart. Thanks.

It is very weird though to see a motherboard with onboard IDE but not floppy.

I believe it's just because of the simplicity of the IDE.
It's just ISA plus a simple address decoder made from discreet parts.
A floppy controller needs a real FDC controller chip, I guess.

Edit: Picture attached. My MTM2183M CD-ROM interface card (IDE/ATAPI) consists
of a PAL16L8ACN, a HD74LS08P and an SN74LS245N.

abasak wrote on 2022-04-14, 20:17:

Yes of course, how stupid can I be… brain fart. Thanks.

no worries - it's really pretty weird to see a PCI baord with enhanced IDE but no floppy, 1st for me.

I do have the FIC 4386 which might be one of the few somewhat "retail, generic, not necessarily OEM" boards that have only a single IDE channel:
https://computer-retro.de/Bilder/Mainboards/H … d-Bios-1992.jpg
- But even that has a floppy port.
While I'm sure there will be dedicated ISA floppy controllers out there, the most common are multi-I/O cards incorporating HDD, floppy, serial, parallel and oftentimes game port.
None of that hurts but you may have to deactivate some of the redundant functions, maybe in the bios settings, to avoid conflict.
Or at leat, make sure you get all the IRQ etc. business sorted out.
If you were to attach four hard drives to the onboard channels, afaik, one more channel could at least be used for CD-ROM drives 😉

AirIntake wrote on 2022-04-14, 20:35:

It is very weird though to see a motherboard with onboard IDE but not floppy.

It makes sense, though. IDE can profit from being closer to the processor than the ISA bus (i.e. local bus or PCI IDE). All the other components you find on a typical multi I/O card are not limited by the ISA bus but the slowness of those interfaces, so it doesn't hurt to have them on the ISA bus. So the cheapest option for a well-performing PCI mainboard is to just take the IDE controller off the ISA bus, but leave the remaining interfaces to a plug-in card. Later PCI mainboard didn't improve on performance of the parallel port, serial port and floppy controller, but they just put the (then available) single-chip multi-I/O controllers on the mainboard, still connected to the ISA bus.

AirIntake wrote on 2022-04-14, 20:35:

It is very weird though to see a motherboard with onboard IDE but not floppy.

It is unusual yes, but in this case it makes perfect sense. The SiS 496 chipset has an integrated local bus IDE controller, but no other I/O functions. It's generally paired with a winbond or UMC super IO chip for the serial, parallel, and floppy support.

a dynamic drive overlay software can be installed to extend the drive capacity limit however it uses a part of system memory to run.

I'd probably do something like stick a floppy/SCSI card in there... since a third IDE interface is not gonna be that useful (Typically can't set tertiary address on "normal" i/o cards, and even if you can, a lot of programs ignore it's existence.) .... mind you, I've probably got half a dozen weird ways to set it up by digging the pile for various i/o combos on various interfaces.

Looks like we have the same board and were wondering the same thing 😀

Adding floppy controller to 486 mobo that has none

There was a short period of time when the integrated IDE without floppy or I/O was common. Asus PVI 486AP4 is another example.

I think it was always kind of dumb idea, as you still end up having to waste a slot for a multi I/O card. But I can kind of see the reasoning. With VLB systems, your IDE/FDD and I/O were all on a single expansion card. But when the PCI boards came along you couldn't do that because PCI is missing some of the legacy signals on ISA that let you operate the FDD and I/O. If you didn't have to integrated IDE, then you'd have to use TWO expansion cards if you wanted to keep IDE on the PCI bus.

I remember there was another "solution" around this time. Rather than integrating the IDE controller, the mother board manufacturer bundled this weird multi I/O card for PCI that "integrates" the floppy and I/O sections by using this dingus that leaches of the ISA bus, effectively stealing two lots anyway. I think it was from an OPTi board, which is typically what you expect with OPTi products.

Anonymous Coward wrote on 2022-04-15, 05:29:

There was a short period of time when the integrated IDE without floppy or I/O was common. Asus PVI 486AP4

bundled this weird multi I/O card for PCI that "integrates" the floppy and I/O sections by using this dingus that leaches of the ISA bus, effectively stealing two lots anyway. I think it was from an OPTi board, which is typically what you expect with OPTi products.

You mean it installed to a shared PCI/ISA slot?
(Which normally couldn’t populate at the same time due to the right handed ISA and left handed pci normally using the same cover position?)

You could be right, it may have been a shared one, in which case only one slot would have been used. It was still wonky as hell though.

It seems that it's not rare for 486 PCI boards to be like this. Same story with QDI MP4-P4U885P3 that I have. When I first got it I thought great, it has IDE so I don't have to mess with I/O cards. And then I tried to plug in floppy 🤣

You should be able to bypass BIOS disk size limits by using a PCI Ultra ATA controller with own BIOS. You could also use SATA controller, but you won't find drivers for Windows 3.1 or 98. The built-in IDE controller should be disabled.

Thanks for all the great replies! I’m trying to find a cheap controller here in EU, but seems like they start at around €50 on eBay.

For a stand alone PCI IDE controller, how do you set the drive size? Is that just automatically detected?

Definitely get a very cheap one. They should cost about €10. There could be incompatibility between PCI spec supported on 486 boards therefore you don't want to spend too much on it. First look whether you are able to disable the internal HDD controller in BIOS so that Hwinfo doesn't detect it (boot from floppy once you have a floppy controller). I just bought three of them and I'm going to test how they work.

Try to look at allegro pl. It's a Polish website (I'm not Polish and I have to use google translate to use it) and prices are very low. E.g Pentium III is much cheaper than on ebay. I have ordered car parts from it before.

If you search for "Kontroler 4xPATA Leadtek WinFast ATA100 do PC " it will show you one item for 40 zł = € 8.6 . It has Silicon Image chip and a BIOS. Another one on sale there is "Kontroler ITE IT8212F ATA 100/133 + RAID" and "Kontroler PCI-IDE CMD 0649".

With PCI Ultra ATA controller you will disable the built-in controller and set hard drives to NONE in motherboard BIOS setup. Ultra ATA controller notification should be shown during BIOS post, either auto-detecting drives or offering its own setup after key press. Ultra ATA controller also needs to install its own Int 13h handler to process hard drive access calls. I'm not sure how it will coexist with floppy controller as Int 13h is meant to handle both.

I've had great results using a Promise Ultra133 card on my SiS496 board

Thanks for the allegro-hint! Much appreciated! I will definately check that out.