mitton@nac.dec.com (Dave Mitton) (03/31/88)
In a recent posting: >Path: decwrl!labrea!agate!ig!uwmcsd1!tut.cis.ohio-state.edu!husc6!cfa!ward >Subject: Re: Thinwire ethernet: Question about drop cables >Posted: 23 Mar 88 17:27:34 GMT >Organization: Harvard-Smithsonian Ctr. for Astrophysics > >I have some DEC printed matter which says that it is permissible to use >a thinwire ethernet tee connector stub cable of <== 27 inches. > >I am installing some thinwire connections to VS2000's and some PC Clones >to talk to a VAX server. The statement is made in documents that came >with the DEC hardware/software packages for the PC support, the names >being something like "VMS Services for MSDOS" (server software which >runs on VAX) and "PC Network Integration Package." I would like to know exactly (eg: Title, Order #, page & paragraph) where you are getting this information from. I do not belive that we have endorsed Thinwire stubs. Quite the contrary, to the best of my knowledge, a tee is the longest stub allowed. Don't confuse the rules of _radial_ thinwire branches from a DEMPR (Multiport Thinwire Repeater) with stubbing off of a daisy chain. Dave Mitton, DECnet-DOS. BTW: Thinwire didn't exist at the time of the original Ethernet standards. It was added in the IEEE under the name of 10BASE2.
wunder@hpcea.CE.HP.COM (Walter Underwood) (04/01/88)
BTW: Thinwire didn't exist at the time of the original Ethernet standards. It was added in the IEEE under the name of 10BASE2. Nope. CheaperNet was invented by 3COM. Traditional Ethernet HW was much too expensive for connecting PCs. The IEEE included it as an option in 802.3. wunder
rpw3@amdcad.AMD.COM (Rob Warnock) (04/06/88)
+--------------- | > BTW: Thinwire didn't exist at the time of the original Ethernet | > standards. It was added in the IEEE under the name of 10BASE2. | Nope. CheaperNet was invented by 3COM. Traditional Ethernet HW was | much too expensive for connecting PCs. The IEEE included it as an | option in 802.3. | wunder +--------------- ACTUALLY... the original project within Xerox for the "enhanced" Ethernet (the 10 Mb/s one instead of the 3 Mb/s "Experimental EThernet") WAS for a "thinwire" net, with much the same advantages/limitations as current cheapernet (which was a term in common use before 3Com claimed it), namely, only about 40 or so taps per cable, and 100-200 meters of cable max. As I understand it, it was primarily DEC's influence in the "D-I-X" troika which led to the current (overdesigned for my taste) long, "thick" Ethernet. Anyway, DEC's idea was to go for the larger-scale net (both in number of taps and length of cable), on the assumption that the resulting high cost of cable and transceivers (due to the tight tolerances required) would quickly come down as volume built up and some chip vendor "integrated" the transceiver. Well, it happened, but not as fast as anyone hoped, so Ethernet got a (largely undeserved) reputation for being "expensive". It didn't help that early 3rd-party controller WERE exhoritantly priced. The actual Ethernet send/receive function has never been as hard to do as even an ST412 disk, and from technology considerations alone, the "right" price for a SCSI-Ethernet controller was the same [at any given point in time] as the price for an SCSI-ST412 disk controller, say, $250 in 1982 (in 1982 dollars), EXCEPT... that the perceived high price of Ethernet never generated the volumes that were needed to get disk controller manufacturers interested in it... until the recent Western Digital controller... The internal Xerox 10 Mb/s wire would have been cheaper than current "cheapernet". (Of course, the original thin wire transceivers might not have passed the new FCC RFI/EMI specs that were just coming out about that time...) Rob Warnock Systems Architecture Consultant UUCP: {amdcad,fortune,sun,attmail}!redwood!rpw3 ATTmail: !rpw3 DDD: (415)572-2607 USPS: 627 26th Ave, San Mateo, CA 94403