Emulation doesn't work with Symbolic 3640

[dgesswein]

The front end processor can read multiple disks OK but the Lisp processor gives error Error: %DISK-ERROR-STATE-MACHINE during a %DCW-UNIT on unit 1, cyl 0, surf 2" (or surf 3 or 4, depending.)

So far have not been able to determine what the cause of the error is.