PDP-11/45 RSTS/E boot problem

Fritz Mueller fritzm at fritzm.org
Wed Feb 13 20:18:02 CST 2019

On 2/13/19 5:20 PM, Jerry Weiss wrote:
> I am trying to understand how the diagnostics didn't reveal this 
> defect.  I see in the source for the diagnostic DZRKH-F there are tests 
> for address in the 28K-32K range and also for the 32K boundary.

So, to catch this defect the diagnostic would have to have a test or 
tests which crossed _specifically_ the 30K boundary within a transfer.

The detailed symptom was a false overflow into the ex.mem bits on the 
30K boundary, causing a skip forward in bus addresses during the transfer.

The detailed fail on the 7430 (E34 on the M795) was that it acted as if 
input pin 11 was always H.

Now, all this said, I don't think I have ever run ZRKH!  I *did* run and 
pass the earlier ZRKA, ZRKB, and ZRKC, but somehow missed ZRKH...  I'm 
wondering now how different it is from ZRKC?  Will have to take a look...


More information about the cctalk mailing list