Date: Mon, 28 Jan 2002 16:07:14 -0800 From: Justin C.Walker <justin@mac.com> To: <hackers@FreeBSD.ORG> Subject: Re: OS Textbook FreeBSD Appendix Message-ID: <2652E782-144C-11D6-B323-00306544D642@mac.com> In-Reply-To: <Pine.LNX.4.33.0201281546400.22257-100000@snaresland.acl.lanl.gov>
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On Monday, January 28, 2002, at 02:49 PM, Ronald G Minnich wrote: > On Mon, 28 Jan 2002, DOROVSKOY,IGOR (A-Portsmouth,ex1) wrote: > >> I've took a brief look on Unix presentation and was wondering, why >> author >> says that "...most Unix systems have not permitted shared memory >> because >> the PDP-11 hardware did not encourage it..."? > > where'd they get this? that's an odd statement. Shared memory was used > all > the time on Unix on -11s, that's the whole point of the shared text > a.out > format. Of course shared read-only text is not exactly the standard > shared > memory, but at the same time it shows feasibility. The address space was > so small though that other mechanisms were used. I'd guess that the point deals with the use of "shared memory" between processes for the purposes of sharing data. Given the granularity of the PDP-11 "VM" hardware, it seemed like a bad tradeoff, and wasn't considered useful until long after the PDP-11 went to the Boston Computer Museum, where it sipped tea and complained about the Red Sox. Regards, Justin -- /~\ The ASCII Justin C. Walker, Curmudgeon-at-Large \ / Ribbon Campaign X Help cure HTML Email / \ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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