test-drb March 2001

test-drb@ccmp.vtda.org

214 participants
552 discussions

Slapping a BSD file system on a disk ...

by spectre＠stockholm.ptloma.edu

Any way I can put a BSD filesystem on a floppy from the Sun boot monitor? *hoping* -- ----------------------------- personal page: http://www.armory.com/~spectre/ -- Cameron Kaiser, Point Loma Nazarene University * ckaiser(a)stockholm.ptloma.edu -- You've got to have a gimmick if your band sucks. -- Gary Giddens -----------

24 years, 1 month

And someone has one... Re: Virus Alert !!!

by ajp166＠bellatlantic.net

From: Sellam Ismail <foo(a)siconic.com> >On Wed, 7 Mar 2001, John Foust wrote: > >> Why fault Microsoft for making products that are popular and common? >> You might as well blame Ford for drunk drivers. I agree that Outlook > >If MS would just give us the source code, we could fix it for them. > >Sellam Ismail Vintage Computer Festival Dont need no speghetti code to fix it. Just remove the dumb user. Seriously, there are a bunch of things that users should to to elimintate most of the insanity. -Disable VBS scripting, that stops a raft of buggies right there. - disable open after preview for 5sec . - disable auto display of pictures - enable empty deleted folder on close (delete really does then). Thats just a few of the simpler things that really do help. Another is dont run MacAfee antiVirus as it has failed on test systems where Norton or Fsecure did catch it. Allison

24 years, 1 month

10Base5/Thicknet (was Re: SUN networking problems)

by ajp166＠bellatlantic.net

From: Bill Gunshannon <bill(a)cs.scranton.edu> > >Actually, as coax for RF purposes, it's junk. It is the lossiest of It's not all that bad but my use would be for a colinear array and lossy cable does work ok there even at uhf. >it weren't so lossy, it would be connected to one of my antennae right >now. Still beats RG58A/u though 50ohm .500 hardline is a prefered wire. Allison

24 years, 1 month

10Base5/Thicknet (was Re: SUN networking problems)

by ajp166＠bellatlantic.net

From: jpero(a)sympatico.ca <jpero(a)sympatico.ca> > > I haven't been following this thread as close as I should. > > I was working at Intel during the period when ether net was just > > being defined. The reason for the 2.5m spacing was to insure that > > any collision was detected by all of the unit on the wire. > > The idea was that the pulses would be exactly overlapped. This was > > In that case, surely the correct spacing of transceivers would depend on > the velocity factor of the cable. And while the stnadard specifies the > spacing (2.5m +/- 5cm IIRC), it doesn't specify the velocity factor > (other than it must be greater than 0.77 IIRC). I recall that in musical stuff and in wirings often these waves travelling in any tube or wirings tend to be standing waves that why that marking is where the amptitudes is greatest. Standing waves in this case would be a reflection of poor termination and cause errors. The measure was to inustre that using the resolution of the system you could resolve to half the distance of a tap (1.25 meters or less than 5ns). The velocity factor of the specified cable doesnt vary much or at least not much if it's in spec. FYI yellow pipe is very good cable. I could use 100ft of it right now. Allison

24 years, 1 month

10Base5/Thicknet (was Re: SUN networking problems)

by pete＠dunnington.u-net.com

On Mar 23, 17:42, Bill Gunshannon wrote: > > Two points. > > First, "a piece" of yellow cable won't work. The lengths were part of the > spec and very important. Having to do with reflections and such (anybody > here still have a TDR??) I've not seen anything about lengths, except of course for the maximum length and multiple-of-2.5m tap separation. I'm told the standard specifically allows for lengths to be joined at intervals which are *not* multiples of 2.5m, and the overall length does not have to be an exact multiple either. > Second, The cable is marked with black stripes. The taps must go on these > stripes. While I have known people who put the transcievers with the N > type connectors between yellow segments and on the ends of yellow segments, > I have never known seen it recommended that you could/should cut the cable > to insert one of these. I fear that after one or two of them, you would > move the spacing between tap locations enough to adversely effect your > network. I've never been aware of a problem with that. Our old Departmental network (installed by my predecessors) consisted of several segments, many of which had lots of N-series transceivers in them. I suppose, though, that when using N-series transceivers, it might make some sense to chop out a small piece of coax rather than just cutting it. I don't have a copy of the standard, and I don't know if it specifies vampire taps rather than the "taps" with N-connectors (which I dare say are more properly called "tees") but I do know that it specifically allows a segment to be made up of sections of cable joined with N-connectors, and that simple joins do not have to be at multiples of 2.5m. Admittedly, good practice was to use the same cable (ideally from the same drum) for each piece, to prevent small impedance mismatches. To do the maths, I find that the velocity factor for RG8/11U is 0.78, the standard value for c (velocity of light in vacuo) is 2.998 x 10^8 ms^-2, and the nominal frequency used for Ethernet is 10MHz, or 10^7 Hz. So one cycle of the waveform occupies 0.78 x 2.998 x 10 m, which is 23.38 metres[1]. That sounds about right; that would mean about 21 cycles over a 500m length. But there's no obvious relationship between 23.something metres and the 2.5 metre separation distance, it's about 1/9th. From that, I can't believe that a small deviation in separation distances is going to make a significant difference. Unless someone can correct my assumptions, of course! [1] Nitpickers might point out that my figure for the velocity factor is less accurate than the 4 significant figures I used for c. So if I take extremes (still within the Ethernet spec) at 0.77 and 0.80, the results would be 23m and 24m respectively. > This is, of course, assuming a production network and not two machines. > But then. if all you had were two or three machines, a couple hundred > feet of yellow cable seems pretty silly. Unless they're a long way apart, or you're doing it for demonstration/nostalgic/"because it's there" purposes :-) -- Pete Peter Turnbull Network Manager Dept. of Computer Science University of York

24 years, 1 month

Some classic pictures

by optimus＠canit.se

In case anyone's interested, we've added some pictures of our new headquarters at http://www.sua.f2s.com/fotografier/. Some pictures of fancy classic equipment, as well as more contemporary junk. The pictures were grabbed with a video camera, though, so the quality is not all that high. -- En ligne avec Thor 2.6a. G? med i SUGA, Swedish Usergroup of Amiga! WWW: http://swedish.usergroup.amiga.tm/ BBS: 08-6582572, telnet sua.ath.cx, port 42512.

24 years, 1 month

10Base5/Thicknet (was Re: SUN networking problems)

by pete＠dunnington.u-net.com

On Mar 24, 15:07, Dwight Elvey wrote: > I was working at Intel during the period when ether net was just > being defined. The reason for the 2.5m spacing was to insure that > any collision was detected by all of the unit on the wire. > The idea was that the pulses would be exactly overlapped. As Tony has already pointed out, that can't be completely true, because it would depend on the velocity factor of the cable, and the standard does indeed specify only a minimum of 0.77 for that. Typical values for thick ether are 0.78-0.8, which gives quite a variation. In addition, it would require that pulses from two stations be in sync, which is unlikely since there's no master clock. > This was > also the reason for the maximum length without repeaters. The > packet size was such that any collision was sure to be detected, > regardless of where one was along the cable. Actually, the minimum packet size is what determines the maximum total length *including* repeaters. The maximum length *without* a repeater is determined by the signal losses. > It doesn't make any difference where the end terminations are > placed but both ends need to be terminated. That's my understanding, too. -- Pete Peter Turnbull Network Manager Dept. of Computer Science University of York

24 years, 1 month

Free DEC docs and equipment, Washington DC area

by CLASSICCMP＠trailing-edge.com

OK folks, time to clear out more of the basement. First of all, all of the below is *FREE*. But there is one gotcha: if you want any of the documentation, you must haul away some hardware too. No ifs, ands, ors, or buts about this. No shipping, no holding, first-come, first-served. Pick-up only, I'm literally a feet away from the Washington DC Beltway (495). Now, the docs, all in original shrinkwrap: KA660 CPU Module Technical Manual (EK-KA660-TM.001) 660QH Pedestal System Illustrated Parts Breakdown KA660 CPU System Maintenance (EK-398AA-MM.001) MS650-AF/BF/BH/BJ MOS Memory Option VMS Installation and Operations: VAXstation I, II, II/GPX and Microvax I, II DECVoice Software Reference Manual Additionally, not in the original shrinkwrap: A big box full of DEC Rainbow and Pro 350/380 binder boxes, some with software. And the hardware: Two BA11 10.5" high Unibus chassis, with power supplies and backplanes. (Weight 60-70 lbs). At least one spare power supply for the above chassis. A couple of Unibus backplanes in various conditions. A 4-foot high tape hanging rack for 9-tracks. Nice wood trim. A whole bunch of other stuff that I could probably get rid of right now but don't have the heart to commit to. If you're here with a truck and ask me about it, though, it's probably yours. If you're interested, please send an E-mail to "shoppa(a)trailing-edge.com". Pick up will have to be on the weekend or possibly a near-future weeknight. Tim. (shoppa(a)trailing-edge.com)

24 years, 1 month

VAXstation 3200

by ip500＠home.com

I've been following the thread about Chad's VAX and/or DEC machine. Just picked up a pair of these VAX station 3200 and don't find much web based data about them. I assume as they clearly say VAX , that they run VMS. Anything I should know before taking a look inside? I don't want any of that magic smoke to escape because of a stupid error on my part. Thanks, Craig

24 years, 1 month

10Base5/Thicknet (was Re: SUN networking problems)

by pete＠dunnington.u-net.com

On Mar 24, 9:44, Bill Gunshannon wrote: > On Sat, 24 Mar 2001, Pete Turnbull wrote: > > I've not seen anything about lengths, except of course for the maximum > > length and multiple-of-2.5m tap separation. I'm told the standard > > specifically allows for lengths to be joined at intervals which are *not* > > multiples of 2.5m, and the overall length does not have to be an exact > > multiple either. > > Well, I could be wrong, but back in the days when I actually did this > stuff for real I know I never saw yellow cable sold in bulk. Only in > fixed lengths. As far as I've seen, it's always been available in 100m and 500m drums -- which of course happen to be multiples of 2.5m -- but I'm sure that's just because they're nice round numbers. Most cable is sold in those quantities. One of my catalogues does list 10,20,30, and 40m lengths fitted with N-connectors, but again I'm sure that's just because they're round numbers. > One would hardly expect they did this if there was no > reason for it. I doubt I still have any catalogs from those days to > look at. In any case, I doubt anyone is going to do a real network today > with an really long sections of yellow cable. > > I've never been aware of a problem with that. Our old Departmental network > > (installed by my predecessors) consisted of several segments, many of which > > had lots of N-series transceivers in them. I suppose, though, that when > > using N-series transceivers, it might make some sense to chop out a small > > piece of coax rather than just cutting it. > > Boy, that sounds scary. But then, what you see in practice does not > always reflect good practice. Agreed, but that was *common* practice. > In the early days of ethernet, all kinds > of strange (and even dangerous) things were done. Like grounding both > ends of the yellow cable (no, you are not supposed to do that!!) Yup, I know! I saw what hapenned when someone tried that :-) It did *not* do anything any good at all! I also know what can happen when the unwary (in this case, me) touch the screen while holding on to a locally-earthed cabinet :-) > Or thin-net installations with a length of RG58 between the T-connector > and the transciever. I know someone who tried that, too. It worked for a couple of short tees, but after that everything fell apart. I know of a few installations which use Safernet and EAD cable to prevent people trying it. > > Unless they're a long way apart, or you're doing it for > > demonstration/nostalgic/"because it's there" purposes :-) > > > I can see doing for demonstration purposes, but I would bet people would > be more impressed if it was fiber. That's what I use small demos. I have a pair of FOIRL transceivers and some fibre for exactly that, but people still are interested to see real Ethernet. > And I may be able to find stuff (like vampire taps) at work as > although it is all inactive, I doubt that the yellow cable has been > removed from the ceiling and wiring closets. Who knows, maybe they > would even be glad to have the yellow cable pulled out too. It's a > pretty long run (the length and height of the building) in two sections. I'd like to get a vampire tap for my collection -- all of ours were N-series, at least all the ones I've found. -- Pete Peter Turnbull Network Manager Dept. of Computer Science University of York

24 years, 1 month

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test-drb March 2001