i186 in circuit emulator recommendations

If you're using it for production debug, you can get nearly the same results by just wiring a logic analyzer to a chipclip and hooking that onto the board's flash/EPROM program chip.

Connect the address and data lines to the inputs, qualify OE/ with CE/ and use that for your clock. Set the logic analyzer to state and format it to show the address and data lines as hex or binary.

Arm the analyzer and hit reset on the target board. After some garbage, you should see the address lines go to 0xFFFF0 and data to the first byte of code.

With a hex listing of the code, you should be able to find bad address and data lines, etc.

I've done it and it works.

I've done it, and it works for a few instructions. After that it gets dodgy.

My project has been using two Noral 186 emulators for years but one now only works with hot air blown on it and the other is getting a bit twitchy as time goes on. We've been looking at replacements and the availalbe brands seem to be: Hitex, Ceibo, iSystems, Signum Lauterbach. You'll be looking at GBP5K for the cheaper ones and 20K for the Lauterbach but it is very good apparently.

We have an 186EB attachment for our broken Noral emulator as well so we could have sold it to you if it worked :-( If you can find a secondhand one somewhere we might be able to help out.

What are you up to with your processor? Sounds like mischief to me ;-)

It's an old embedded system which has basically no debugging hooks and has recently acquired a high failure rate where the system seems to load the first bit of the instruction stream correctly, but runs off into the weeds sometime before empowering any of the functionality that would allow us to debug the problem.

I bet it doesn't do it with the emulator :-p Can you make "breakpoints" in the code that would wait for a pin to be toggled by a switch before progressing? That way you can break down into blocks to narrow down the problem.

Or a cheap quick test might be buying a different manufacturer's 186 clone and sticking it in to see if the problem is still there.

It comes with the boot sector stuff preloaded in the eprom, so changing that is basically impossible - and it's functionality for loading code depends on it successfully getting through the initialization sequence.

In an old system that used to work fine and if initial boot code hasn't changed, then it's probably hardware related. Most likely some device out of spec or similar. What have you changed, either chip vendor or pcb ?. For example, is the device that the boot code loads from the same spec in terms of access time ?.

A logic analyser is probably the best tool. An ice introduces it's own timing skews...

Chris