Almost every pin I need is accessible via the headers - except one, and its one I kinda need. It's the D/C or Data/Code pin. The 386 no longer emits an octal bus status like the Intel chips before it did; instead it emits bus signals directly.

The Data/Code pin tells us whether the current bus operation read is just reading memory or fetching code. That's important if we're going to feed the CPU instructions.

It's not strictly required if we just emulate memory, but its nice to have as just feeding the CPU code bytes when it is fetching is convenient as the address doesn't matter.

If we're going to make 386 tests as well, this is an important pin to capture the state of for that purpose.

They wouldn't really have needed it to build this board. There's no reason to concern the SRAM with whether its serving up code or data. So likely it just goes nowhere.

So that means I have to solder a wire to this...

Let's make sure we absolutely have the right pin.

A good sanity check is that VSS connects to at thick ground copper, and M/IO connects to a via, that we can trace out going to the correct header pin.

OK, without any clock source this thing should barely draw any power.

Half a watt seems about right. Much more reassuring than the 286 was!

This is a 3V capable CPU though, so we'll run the board at 3V. It draws 0.1 W at 3.3V which is even better.

Still wondering what happened to my 80C286. Wish I had a system I could throw it in to see if it was actually dead or if I'm just a bonehead.

here's what i have to patch over to the Arduino

50% chance i have one or both of the address headers backwards lol