PDP11 I/O page memory map

allison allisonportable at gmail.com
Thu Mar 1 05:12:00 CST 2018

On 02/28/2018 08:15 PM, Douglas Taylor via cctalk wrote:
> Is there a document that describes the bank 7 memory page and what
> addresses are reserved for what?  I think I've seen this before but
> can't seem to put my hands on it.
> Another question, bootstrap is reserved for 173000, how many words are
> allowed there for this?  How do the more complicated bootstraps, e.g.
> microPDP11-53, accommodate this limitation?
> Doug
I strongly suggest RTFM the PDP-11 handbooks.

Till you do...

Page 7 is  the upper most memory area and is reserved as EPROM and IO
peripherals. On many of the
PDP-11s that page is signified by asserting BBS7 ( a partially decode
address) and the MMU also
understands that peripherals live in that physical space be it 16/18/22
bit memory map.

Boot and diagnostic roms are a special case as more often their size was
not limited to the area of bank 7
but the available devices of the day.  They do however map roms so that
they cannot overlap the IO

FYI the microPDP-11/53 is the 11/23+ cpu card so you can look that up.


More information about the cctalk mailing list