General DEC diagnostic questions

I assume these are probably silly questions, but hey, it's just not clear to me :) In the PDP11 diagnostic handbook (1988) on bitsavers, some of the diagnostics mention setting CSR at 174, and SWR at 176 for various options to a given diagnostic. I am assuming that SWR is the console switch register. I thought on a /34 this was off in location 777050 (or something like that). So do I put those options in the keypad and hit LSR (which I thought put them in 777050) or do I need to put them in 176 before starting the diag? Also, is there something special about 174 that I'm not getting? Some of the docs say a particular diagnostic prompts "SWR=000000 NEW="... I assume the diags are querying if I even HAVE a switch register, and if I do, they don't print that question. Correct? Thanks for any education :) J