[HECnet] 2.11BSD

[Johnny Billquist]

On 2012-12-18 15:45, Paul_Koning at Dell.com wrote:

On Dec 17, 2012, at 6:01 PM, Johnny Billquist wrote:

On 2012-12-17 23:50, Boyanich, Alastair wrote:
...
2) Was 2.11BSD ever ported to other platforms? Given the age/era, I'm
curious about 8088/8086/NECv20/80286 given the banked memory models used
and looking at the 8088/8086 XENIX disassembly.

Nope. That would not have been 2BSD then. And since the PDP-11 don't even have banked memory, it would probably cause some headaches to port 2BSD to something like 80286 or other similar machines.
To make it clear - the PDP-11 have a very normal MMU with pages.

Semi-normal.   It's rather unusual in that it has a paged MMU with page address granularity different from the page size (64 bytes vs. 8k bytes).   Most architectures have those two match, that avoids an adder -- consider VAX or MIPS or Alpha.

Details. :-)
Just consider it an extra feature.

However, I think it is actually pretty common in a way today, when you have different page sizes on the MMUs. (But I have not looked exactly how you can use them.)

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                  ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol