First post, by Spyd
- Rank
- Newbie
Some time ago, after some discussion with people about custom-made ISA cards for industrial machinery control, MS-DOS and solutions to replace those computers that are failing, I had an idea, but I don't know how much about its feasibility. So I'm going to throw it here and see what do you think about it.
The gist of it is making a PCB the size of a full-ATX motherboard, minus the size of an mini-ITX motherboard. If it's not clear enough, picture a PCB, with the size of an ATX motherboard but there's a "hole" in the size (and position) of an ITX motherboard.
On this new board, there would be PCI and 16bit ISA slots, ATX mounting holes, an ATX power connector, and a flex ribbon ending with a male PCIe connector.
You would install this PCB on an ATX case with a mini-ITX motherboard, and the flex cable would connect both boards.
On the PCB would be two chipsets and it's supporting passive components: a PCIe to PCI bridge (for example an ITE IT8892E or ITE IT8893E) to power the PCI slots, and a PCI to ISA bridge (for example the ITE IT8888F) to power the ISA slots.
The resulting contraption would be a modern computer with some PCI and ISA slots available. The ISA or PCI cards would install as if the motherboard had the slots itself, without the need for an external enclosure or risers or other inelegant solutions. Also, if the computer dies or you want to upgrade it, you can replace the mini-ITX motherboard, the rest of the PCI and ISA cards you can keep. The ITX motherboard doesn't have to have anything special, no TPM module connector, only a PCIe slot.
Windows (almost all versions) would not have any problems with the bridge chips, as (as far as I know) it has built-in drivers for both of them, so for compatibility, the problems would arise from not having drivers in the most modern versions of Windows for old PCI or ISA cards, but this is outside of the goal for this project. If the card shows on the device manager, it works. You have to provide the correct drivers for the card on your Windows version (if they exist). Also this being a software problem, I'm sure there would be people willing to "port" drivers for old cards to the latest Windows versions.
But from the perspective of trying to make this run on old OSs, specifically MS-DOS and "derivatives" (Win9x) there is where I have the most questions about feasibility.
First and foremost, if the motherboard doesn't have CSM, forget about it. If the motherboard has CSM and it's enabled, you can install MS-DOS. But then, would MS-DOS see or understand the bridges so it can "talk" to the ISA and PCI devices? Would programs that talk directly to the hardware see it too?
I'm sure there's also a million of other stuff that I'm not taking into account, but... does it look feasible or it's not even worth trying? Also, does this look like a project people would be interested in if the boards would be available to order at a board manufacturer?
