Lars Brinkhoff  <lars.spam@nocrew.org> wrote:
+---------------
| Kent M Pitman <pitman@nhplace.com> writes:
| > the 10 was a 36-bit machine with 18 bit addresses, while the 11 was
| > a 32-bit machine with 16 bit addresses, but the instruction sets
| > were wildly different, too.
| 
| I believe the PDP-11 is a 16-bit machine: addresses, instructions,
| and registers are all 16 bits.
+---------------

That's correct. Though in some models there was a larger physical
address space on the bus, e.g., PDP-11/20 Unibus had 18 bits of
physical address, the Q-Bus had 22. These extra bits were accessible
only when using the 8-segment MMU to map virtual (16-bit) addresses
to physical (18, 22, whatever).


-Rob

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