From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 References: In-Reply-To: From: "Digby R.S. Tarvin" Date: Tue, 9 Oct 2018 08:55:05 +1100 Message-ID: To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Content-Type: multipart/alternative; boundary="000000000000ae01800577beabb0" Subject: Re: [9fans] PDP11 (Was: Re: what heavy negativity!) Topicbox-Message-UUID: e8e57f52-ead9-11e9-9d60-3106f5b1d025 --000000000000ae01800577beabb0 Content-Type: text/plain; charset="UTF-8" Does anyone know what platform Plan9 was initially implemented on? My guess is that there is no reason in principle that it could not fit comfortably into the constraints of a PDP11/70, but if the initial implementation was done targeting a machine with significantly more resources, it would be easy to make design decisions that would be entirely incompatible. Certainly Richard Millar's comment suggests that might be the case. If it is heavily dependent on VM, then the necessary rewrite is likely to be substantial. I'm not sure how the kernel design has changed since the first release. The earliest version I have is the release I bought through Harcourt Brace back in 1995. But I won't be home till December so it will be a while before I can look at it, and probably won't have time to experiment before then in any case. For what it is worth, I don't think the embarrassment of riches presented to programmers by current hardware has tended to produce more elegant designs. If more resources resulted in elegance, Windows would be a thing of beauty. Perhaps Plan9 is an exception. It certainly excels in elegance and design simplicity, even if it does turn out to be more resource hungry than I imagined. I will admit that the evils of excessively constrained environments are generally worse in terms of coding elegance - especially when it leads to overlays and self modifying code. PDP11's don't support virtual memory, so there doesn't seem any elegant way to overcome that fundamental limitation on size of a singe executable. So I don't think it i would be worth a substantial rewrite to get it going. It is a shame that there don't seem to have been any more powerful machines with a comparably elegant architecture and attractive front panel :) It is sounding like Inferno is going to be the more practical option. I believe gcc can still generate PDP-11 code, so it shouldn't be too hard to try. DigbyT On Tue, 9 Oct 2018 at 04:53, hiro <23hiro@gmail.com> wrote: > i should have said could, not can :) > > --000000000000ae01800577beabb0 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Does anyone know what platform Plan9 was initially impleme= nted on? My guess is that there is no reason in principle that it could not= fit comfortably into the constraints of a PDP11/70, but if the initial imp= lementation was done targeting a machine with significantly more resources,= it would be easy to make design decisions that would be entirely incompati= ble.=C2=A0 Certainly Richard Millar's comment suggests that might be th= e case. If it is heavily dependent on VM, then the necessary rewrite is lik= ely to be substantial.

I'm not sure how the kernel d= esign has changed since the first release. The earliest version I have is t= he release I bought through Harcourt Brace back in 1995. But I won't be= home till December so it will be a while before I can look at it, and prob= ably won't have time to experiment before then in any case.
<= br>
For what it is worth, I don't think the embarrassment of = riches presented to programmers by current hardware has tended to produce m= ore elegant designs. If more resources resulted in elegance, Windows would = be a thing of beauty.=C2=A0 Perhaps Plan9 is an exception. It certainly exc= els in elegance and design simplicity, even if it does turn out to be more = resource hungry than I imagined. I will admit that the evils of excessively= constrained environments are generally worse in terms of coding elegance -= especially when it leads to overlays and self modifying code.=C2=A0
<= div>
PDP11's don't support virtual memory, so there d= oesn't seem any elegant way to overcome that fundamental limitation on = size of a singe executable.=C2=A0 So I don't think it i would be worth = a substantial rewrite to get it going. It is a shame that there don't s= eem to have been any more powerful machines with a comparably elegant archi= tecture and attractive front panel :)

It is soundi= ng like Inferno is going to be the more practical option. I believe gcc can= still generate PDP-11 code, so it shouldn't be too hard to try.=C2=A0<= /div>

DigbyT

On Tue, 9 Oct 2018 at 04:53, hiro &l= t;23hiro@gmail.com> wrote:
i s= hould have said could, not can :)

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