that will work fine in a passive isa backplane. just get a vga card and your all set. looks like floppy/hd connectors on top. youd just need to figure out the jumpers.

BloodyCactus wrote:

that will work fine in a passive isa backplane. just get a vga card and your all set. looks like floppy/hd connectors on top. youd just need to figure out the jumpers.

Still have to figure out the keyboard connector though...

a _LOT_ of passive industrial isa backplane had the at keyboard connector on it already.

eg:

BloodyCactus wrote:

a _LOT_ of passive industrial isa backplane had the at keyboard connector on it already. […]
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a _LOT_ of passive industrial isa backplane had the at keyboard connector on it already.

eg:

Well that is mighty interesting. I'll have to check to see if any of my backplanes had a keyboard connector, but it looks like that connector isn't integrated into the circuitry; it's taking +5v from the power supply and the rest is possibly connected to the SBC via a cable, which is what I'm hoping is the case with that 486 I bought.

hmm true. i bet one of the 4 pin connectors on the sbc is it.

I did find this:

There's a keyed five-pin connector here that has what appears to be power (red wire) and three data lines; that could be for clock/data/ground. I can probably determine which is power and which is ground easily enough. Not sure how to check clock and data though.

Any idea what type of connector that last picture uses?

I think it may be one of these:

http://www.globalsources.com/gsol/I/IDC-conne … .htm#1071003836

isnt that a 4 pin connector above the cpu?

as for the connectors, you mean the red things? I dont think it matters. the pcb has white molex with locking ramp/locking shoulder. you can just use plain old molex kk headers for the same pitch.

https://www.greatplainselectronics.com/categories.asp?cat=70

It's kind of a beauty! What's the empty socket for? Weitek FPU? i960?

If I were you, I would probably try and use EC type connectors and a flat cable to connect this cool thingy to a video card and a sound card, hang the whole system on the wall and use as a conversation piece as well as a nice retro machine!

Got the card today. It's missing a contact from the first dimm slot:

My only 30 pin DIMM doesn't work in any slot, but it's also a 3 chip DIMM. I've found and purchased a lot of 30 pin dimms off of ebay.

Was it common for 486-era boards to require 4 dimms to be installed or for pairs of DIMMs to be installed?

Since both pin 1 and pin 30 are +5vdc, is it absolutely mandatory that both be available?

Yes it's very common for the 486 to require 4 30 pins ram sticks to work 😀

sunaiac wrote:

Yes it's very common for the 486 to require 4 30 pins ram sticks to work 😀

That's what I thought. Hopefully I can piece together a working set from the ram I have coming in.

The top socket just has to be replaced. 30-pin SIMMs install in banks of 4 on 486 machines.

Damaged SIMM: The pins on the outer side are redundant (5V) - it may work despite the pin missing.
For the keyboard: There should be a 74*07 logic chip near the connectors. The connector in question will lead there. These are the two data lines. 5V and GND will be easy to find.

my 486 SBC works fine with just a pair 30pin simm sticks, you dont necessarily need 4 sticks.

That is likely a 16-bit 486 variant (SLC) though.

considering mine is IntelDX4WB, Id' say no, its not the SLC variant, and it works perfectly fine with 2 banks.

bank requirements are driven by the chipset, not the cpu. Mine is a VIA VT82C496G.

Reading the datashseet for the OP's opti 82c392 (the southbridge), it says

* up to 64mb max dram
* 256 or 512kb cache ram required to cache the full 64mb
* supports 4 banks of ram (which is interesting since OP has 8!)

chipset details graphs supprting 1 bank, 2 banks, 3 and 4 bank configurations. theoretically you can run 1 stick of ram according to the datasheet.

I couldnt find anything on the northbridge chip (495) datasheet wise.

You are mistaking 'bank' with 'stick of RAM'. A bank is usually the width of the CPU bus -> 1 stick [30-pin SIMM] on 8088, 2 sticks on 286, 386SX, 4 sticks on a 32-bit 386/486. Or 1 stick of 72-pin SIMM for the latter. 8 30-pin SIMMS populated on a 386DX/486 will be two banks.

Theoretically it would be possible to split up the transfer to a more narrow bus, but this halves or quarters [or worse] the memory throughput. Of course you can say a snail runs fine though...

thanks. op's board should happily run then on two sticks of ram.