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Xref: sserve comp.unix.ultrix:24272 comp.unix.bsd:15658 comp.sys.dec:24488 comp.sys.dec.micro:3851 Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msunews!uwm.edu!vixen.cso.uiuc.edu!howland.reston.ans.net!pipex!uunet!topaz.sensor.com!topaz.sensor.com!ron From: ron@topaz.sensor.com (Ron Natalie) Newsgroups: comp.unix.ultrix,comp.unix.bsd,comp.sys.dec,comp.sys.dec.micro Subject: Re: UNIX (Ultrix, BSD?) for DEC Micro PDP-11? Followup-To: comp.unix.ultrix,comp.unix.bsd,comp.sys.dec,comp.sys.dec.micro Date: 19 Dec 1994 15:17:54 GMT Organization: Sensor Systems Lines: 33 Message-ID: <3d4872$r81@topaz.sensor.com> References: <taubman.787470030@spot.Colorado.EDU> <arog.787839518@BIX.com> NNTP-Posting-Host: localhost.sensor.com X-Newsreader: TIN [version 1.2 PL2] Well, UNIX came from PDP-11's, but it's been a long time. First off, if you don't have memory management (11/23,73...) it is hopeless. UNIX never really did run well on those things. There were a few aborted attempts (MiniUnix, LSX) but nobody gave them much credence even back when UNIX was small and I doubt that you could find one of those around these days (and they were WE licensed and I don't even thing you could obtain such a license anymore). Even with real memory management, it's hard to do things with a PDP-11 anymore. The problems is that programs have just gotten too big. The PDP-11 memory system is permanently stuck in what 386 people would call small model. Overlays were hacked in to give a lease on life, but you had to make hokey interfaces in the user mode as unlike the 8086, there is no segment facility. What finally killed the 11's for us was that we ran out of segment registers to even play the overlay games. PDP-11's only have 8 (or if your lucky 8 code + 8 data) to muck around with. Each one banks 8K of your 64K address space. Of course, now, they are tremendously slow and under-memoried compared to a PC (they only have a 22 bit physical address bus under the best of configurations). I have great fondness for them. They continued to live on at BRL under my care even after they were replaced by Goulds and Suns for UNIX work as IP routers running my own little operating system (I think that I was the only one who was using an 11/70 as a standalone internet router, but it had the distinction of being the busiest host on the MILNET for quite a period of time, kick-ass performance in those early Internet days) and one even survived as an I/O controller for the HEP supercomputer. -Ron