Talk:10BASE5

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This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.
  • RG is not short for Radio Grade but Radio Guide IIRC

and for the connectors UG = Union Guide

  • asin waveguide

Linuxlad

  • How do you know? maybe the RG stands for Really Good.
    • Not likely. But if you want to find out, you could just look up RG (but the article isn't consistent...) Not that it really matters, it's not RG-anything, and certainly isn't at all like "RG-8X". Paul Koning 01:11, 14 April 2007 (UTC)

[edit] Vampire tap wasn't the only (or original?) way to go

When I first started working with "garden hose" in the mid-1980s, transceivers had screw-thread coaxial fittings, meaning that in order to insert one into an existing run, one had to cut the cable (network down, sorry!), install connectors on both ends of the cut, and attach the transceiver (network back up! ...assuming you did it right the first time).

I don't know (or this would be in the article :-), but my impression is that vampire taps were a later innovation to simplify this process immensely. The transceiver in the picture looks awfully familiar, and I wouldn't be surprised if it isn't the same model of transceiver we eventually adopted; from Cabletron, if memory serves.--NapoliRoma (talk) 05:18, 21 December 2007 (UTC)

I haven't seen the sort of transceiver you mentioned. Who made those? As for "original" vs. "later innovation", probably not. Digital, for one, shipped vampire tap transceivers from the start, and I don't believe we ever considered the approach you described. So perhaps it was a simpler approach used by some other manufacturers, who didn't want to bother to figure out how to make vampire taps work? Paul Koning (talk) 12:04, 21 December 2007 (UTC)
Who made those?
3Com, I'm pretty sure, which puts it essentially right at the origin of Ethernet itself.
Digital was kind of late to the game with Ethernet, weren't they? (And jeezly expensive at first. I remember being quoted a 5-digit figure to get Ethernet/TCP for our PDP-11 RSTS systems—can $50K/system be right?—so they stayed in their own separate DECnet environment for years after everything else was on TCP/IP.) So it's entirely plausible that you had the good fortune to be able to go straight to vampire taps.--NapoliRoma (talk) 15:11, 21 December 2007 (UTC)
I couldn't find a photo anywhere, but here's a drawing...--NapoliRoma (talk) 15:48, 21 December 2007 (UTC)
Well, "DIX" means "Digital, Intel, Xerox". DEC was one of the three companies that created Ethernet. Sure it was relatively expensive; the original DEC Ethernet controller was the DEUNA, which took two "hex size" Unibus controller boards. So at the usual price of $2k per board that ended up a $4000 device. But remember, that was before single chip NICs existed. The first DEC controller that used an approximation of a single chip NIC was the much-cursed DEQNA. It was much smaller, and also so poorly designed that it was finally scrapped after 14 revisions.
It may be that 3Com actually produced the first commercial NIC, before DEC. I don't remember the precise timeline that far back anymore... Having 3Com be first wouldn't be too surprising; after all DEC was a notoriously slow company while 3Com was a hungry startup. Then again, the DEC product worked, and the 3Com 3c501 didn't. (It worked only so long as your application was really really slow -- it had a single packet buffer.)
As for TCP for RSTS, that never was a DEC product. I forgot who sold that. $50k seems outlandish but who knows. Certainly both hardware and software were much more expensive in the minicomputer era than in the PC era.
Paul Koning (talk) 16:31, 21 December 2007 (UTC)
That's what I love about WP: you can learn something new every day... I've managed to go a couple of decades working with Ethernet without ever running across the "DIX" acronym. Apologies for undercrediting DEC here. But yeah, this didn't seem to trickle into their products very quickly, at least not the older ones. I remember I could telnet into our first VAX from day one, though, which was a happy thing.
The first Ethernet NICs I worked with were actually Multibus cards for Sun-2s, which would have been either 3com or Sun's own, according to the WP page; we probably even originally got the transceivers through Sun. But yeah, we eventually wound up buying 3C501s and 3C503s like popcorn once PCs started making their inevitable incursion. (You might be interested to know that after a careful evaluation we originally standardized on DEC Rainbows rather than IBM PCs; seemed like a good idea at the time...)
But I did have a point to all this other than stirring up old brain cells better left in dormancy. In the article, it currently reads

10BASE5 cable is designed to allow transceivers to be added while existing connections are live. This is achieved using a vampire tap

I think this is overstating the case. I don't think the cable or spec was originally designed for piercing taps, but that this was a very clever idea that came later. However, my only evidence at this point is my personal experience (saw and used N connector transceivers first), and some deductive reasoning (why wouldn't you use vampire taps if they were available?). In short, WP:OR at this point. But I think the article should be modified to read something like

Transceivers can be added to 10BASE5 cable via N connectors or with a vampire tap; the latter makes it possible to add transceivers without interrupting existing connections

--NapoliRoma (talk) 17:36, 21 December 2007 (UTC)