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Re: New Vax - future directions :-)

On 2021-07-07 16:12, Hans Rosenfeld wrote:
On Wed, Jul 07, 2021 at 03:51:47PM +0200, Johnny Billquist wrote:
But I still sortof fail understanding why something like the Ragge FPGA VAX
would be interesting to have PDP-11 emulation on. Like I said, I seriously
doubt it would be capable of running early VMS for multiple other reasons.
And the PDP-11 mode in the VAX have limitations that makes it much less
attractive than any normal PDP-11.

Well, wouldn't it be awesome if NetBSD/vax64 can run 2.11BSD binaries

I think you are underestimating the limitations of the PDP-11 compatibility mode of the VAX...

No split I/D space, no FP, any kind of trap exits out to VAX mode, anything that depends how the memory management of the PDP-11 works will have issues... Even some instructions you might play with are missing (but I don't think most people would miss them, especially not since we don't have split I/D space anyway).

Very few 2.11BSD programs would work in this environment... The most serious limitation is the lack of split I/D space.


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

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