Keyboard Failure on 386 SBC, help identifying jumper settings

[NTICompass]

I picked up a 386 SBC from eBay the other day. The seller said it was pulled from old lab equipment and that they didn't know if it worked and didn't have any documentation for it.

I don't know the jumper settings, I don't know what any of the pins/headers are for, but I decided I'd try firing it up anyway... what's the worst that could happen?



From Mouser, I picked up a ISA backplane (Advantech PCA-6108-0B2E) and connected the SBC, a video card, an AT keyboard and an AT PSU.



To my surprise, the system actually POSTed! It counted up its 8mb of memory... while showing me a "keyboard failure" error. I don't know if this is an issue with the backplane, the SBC, a jumper setting or what. I tried using an XT keyboard instead, I didn't think it would work... and it didn't. Neither did a PS/2 keyboard in a PS/2 to AT adapter.



How can I get around this "keyboard failure" error? Does anyone recognize this SBC? Is there a jumper I need to change? Is something wrong with the [keyboard] BIOS? Is something wrong with the backplane? The backplane does have a connector for a PS/2 keyboard dongle or something, but I don't have the correct cable and I don't even know if the SBC would like the a PS/2 keyboard. Is there maybe a PS/2 ISA card I can use?

Can anyone help me out here?



Here are the specs:

• SBC: TMI Industrial Computer 572-A-0301-H (572-DGA-301-202)
• CPU: Intel A80386DX-20
• FPU: Intel A80387DX-20
• RAM: 8 x 1MB
• Chipset: Chips & Technologies CS8230
• ISA Backplane: Advantech PCA-6108.Rev.B2

UPDATE: I found the manual for the backplane: https://advdownload.advantech.com/pr..._Notes_ed1.pdf

It lists multiple KB connectors (one being PS/2) and the "external" AT connector.

 

[Chuck(G)]

Well, here's a guess...

What's the connector on the bottom to the left of the ISA edge connection? Looks to be an 8 pin job. Could it be similar to the 8-pin connector on TMI's 80286 system? See PDF page 38 here. Given that Industrial SBC makers tended to keep backplane designs for a long time, I'll bet that it is.

Also, see the TMI N286 SBC pictured in this auction See the connector?

 

[NTICompass]

What's the connector on the bottom to the left of the ISA edge connection?

You mean this white thing? I was curious about what this was, I didn't have any idea.
Are you saying I need to connect one of the KB connectors on the backplane to this white connector?

EDIT: Oh, I think I see what you're referring to... you think this connector is the "RAMSEL" pins?

 

[Chuck(G)]

J3 on the extreme right side of the schematic. Also called out for the N286 on Vogons J5

 

[NTICompass]

J3 on the extreme right side of the schematic. Also called out for the N286 on Vogons J5

Ah! Thanks. I didn't see that. This looks very curious!
I guess I can try to use a multimeter to see what the pins are, or try to short the reset ones and see if it resets. It would be nice if this was the solution!

 

[NTICompass]

Also, see the TMI N286 SBC pictured in this auction See the connector?

Ooh! This does look extremely similar to the connector on my board! I'll try to detect if the pinouts match.

 

[Chuck(G)]

You really don't need to verify much. They're identified on both the schematic and on the Vogons info page

Check the GND, +5 and Reset pin (by grounding it) and you should have all you need to know. Texas Micro sold their own backplanes and boxes, which is why the connector is used. Advantech obviously went a different route, but you can probably adapt things to use the rear DIN connector on the backplane.

 

[maxtherabbit]

I think Chuck nailed this one. The 5-pin JST XH connector on your backplane is the defacto standard for keyboards on modern ISA backplanes. It should be easy to make an adapter harness to go between the two

 

[NTICompass]

I think Chuck nailed this one. The 5-pin JST XH connector on your backplane is the defacto standard for keyboards on modern ISA backplanes. It should be easy to make an adapter harness to go between the two

I have jumper wires that I can connect between the backplane and the SBC. I didn't know that the AT keyboard signals didn't travel over the ISA bus, but instead over their own connection.

 

[NTICompass]

[...] You can probably adapt things to use the rear DIN connector on the backplane.

YES! I was able to do that! Thank you so much, with your help I was able to get the keyboard working.

This board is in fact a Texas Microsystems one (I guess the "TMI" should've been a hint). Anyway, this means that the 8-pin connector was exactly the same as the one you suggested to me.

I was able to connect jumper wires from the KB connector on the backplane to the connector on the SBC and the keyboard works :-D

I was also able to hook up the PC speaker and the reset button


I took 2 jumper wires from the data/clock and sent them over to the SBC. The red/black wires are +5/GND directly from the PSU.


On the SBC, I used (different color) jumper wires to connect the KB data/clock signals and it works!