PDP-11 addressing question and a model round-up

[Vintage Computer Festival]

I didn't want to spend time researching this since it's not that important
and I figure I can get a quick answer here.

With the MXV21 controller I have, I needed to poke words into its
registers to format a disk.  The manual instructed to poke the words in
the 177xxx range.  But when I tried this nothing happened.  I scratched my
head and then remembered from a previous helpful message someone talked
about how the addresses also map to higher memory sometimes.  So I
tried poking the words in the equivalent 377xxx range and it worked.
What's going on here?

I'm not sure how widely known this site is, but here's a really nice
website on the PDP-11:

Yet Another PDP-11 Page
http://www.psych.usyd.edu.au/pdp-11/

The "Production Models" link leads to a nice round-up of all (most?) of
the various PDP-11 models, which includes basic information and links to
photos and more detailed information on certain models.  Now I have a
target list of models to acquire...8 down, 14 to go ;)

Also includes a nice page of tips for the RK05:

http://www.psych.usyd.edu.au/pdp-11/rk05_internals.html

And bootstrap loaders for a bunch of storage devices:

http://www.psych.usyd.edu.au/pdp-11/bootstraps.html

-- 

Sellam Ismail                                        Vintage Computer Festival
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International Man of Intrigue and Danger                http://www.vintage.org

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