VAX-11/730 %BOOT-F-Unexpected Machine Check

I finally got the excellent AK6DN tu58em emulator working as my VAX-11/730's console drive, as discussed on VCF. The trouble appears to have been a simple timing issue: tu58em includes some time delays which run afoul of the 730 console's very aggressive timeout checking. After patching in a command line flag to disable them, my 730 console seems to be happy with tu58em running on my MacBook Air over an FTDI USB/RS-232 converter. I've also tweaked the FTDI's driver settings to make sure that latency is minimized, but I'm not sure if I changed it significantly from the default. But the console appears to time out if the tape drive takes 20ms or more to respond to the initialization sequence, so every millisecond might impact reliability. With the console working and loading up a version 57 11/730 console tape image that I found online, I've been trying to boot the machine up. When I try to boot from either the R80 or RL02, I get error message "%BOOT-F-Unexpected Machine Check". Does that error message mean anything to the VAX experts out there? This machine was believe to be working before time + transport, and I'm trying to bring it up for the first time since I got it. I still have a lot of learning curve to climb, but I'm excited to have made more progress. -- Mark J. Blair, NF6X <nf6x at nf6x.net> http://www.nf6x.net/