PDP 11 RL11/01 Address confusion.

Hi Everybody I was reading some doco last night (specifically the DEC RL11/01 Disk Subsystem Training Handout), and I am confused. (That is nothing new...) In the "Subsystem commands section", the addresses specified for DAR and CSR are 774404, and 774400 respectively, but in the back of the document, under the 'toggle in programs' section, the DAR and CSR are shown as being at 174404 and 174400 respectively. Hmmm. I see three possibilities: 1. I have (re) discovered a documentation error - I wonder if DEC, no, HP, no Compaq, would be happy for me to submit an amendment :-) 2. The hardware throws away the upper bits so both references are correct. Hmmm Possibly not :-) 3. There is some other stuff happening that I missed... If anybody could shed some light on this I would appreciate it. The background to the problem is that I can not convince my shiny, wonderful, (and noisy) DL01 to perform the seek test - Me thinks there is a problem.... Doug