strange number corruption on pdp11/34 - test-drb@ccmp.vtda.org

30 Jan 2015

-----Original Message-----
...
 From: Noel Chiappa <jnc at mercury.lcs.mit.edu>
Sent: Jan 30, 2015 5:19 AM
To: cctalk at classiccmp.org
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: strange number corruption on pdp11/34

  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? 
Disassembled and re-commented source. Available here:

  http://ak6dn.dyndns.org/PDP-11/M9312/

along with most all of the other M9312 boot and device PROMS.

...

  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 