On the Duo230 again:

I installed Macsbug

After the adb: cleanup: nothing returned messages, I pressed cmnd-<power>
(I guessed at the combination!) and got the following result:

Panic Switch: PC is 0x96562
Stopped at      _Debugger+0x6:  unlk     a6
db>

(Is this Macsbug?) At this point, the keyboard is useless.

I had Boot Echo on, but no output on the serial terminal.

There was some diagnostic info at the top.  If anyone wants me to give it,
I can.  Tell me what info you want.

If it is useful, I get the following HwCfgFlags:
    0xed00, 0x     773f, 0x     130112, 0x    ac3e28

It identifies the Duo 230 and the amount of memory correctly.

It also says it is moving the ROMBase from 0x40800000 to 0x9f7000

mrg says it is skipping egret setup

There's more.  Just tell me what you would like to see!

Thanks,
Rich