From: Don North 
  So here is the octal print routine in the M9312
console boot prom for
 the '34: 
I'm curious, is that the 'original' source, or is this dis-assembled from the
PROM contents? Is the complete program available somewhere?
  So I would speculate either 'rol' or
'rolb' are always rotating in a 0
 bit instead of the c-bit, or possibly the c-bit is stuck at zero. 
Yup, good suggestion. And that would likely explain why things boot; I can't
see too many OS's using 'ROLB'!
        Noel