Talk:10BASE2

rounding

I made a change which I thought made it more readable, but was reverted. The original, and now reverted text, says: and the 2 supposedly refers to the maximum segment length of 200 meters, though in practical use it can only run up to 185 meters. (The IEEE rounded 185 up to 200 to come up with the name 10BASE2, for consistency with the general standard). The maximum segment length in the standard is 185m. It will work on longer runs with better cable, and shorter with lower quality cable, but the number is 185m. They could have named it 10BASE1.85, but decided to round it to 10BASE2. (I prefer lower case, as in 10base2, the IEEE seems to disagree, but that is a different question.) The 2 comes from rounding 1.85 up, the standard never says that it is 200m, or that in practical use it can only run 185m. The current text seems a complicated way to say that it is rounded, while implying something that the standard does not say. Can we do better? Gah4 (talk) 03:49, 3 October 2016 (UTC)

Perhaps a simple "and the 2 refers to the rounded up maximum segment length of 185 m"? You're right that the text is inacurate as it says 10BASE2 is supposed to support 200 m but doesn't in practical use. --Zac67 (talk) 09:33, 3 October 2016 (UTC)

"(the actual maximum length is 185 m)" has been added. ~Kvng (talk) 15:31, 28 May 2020 (UTC)

Network design section, termination, reflections ,and all that

It is possible to have a 10BASE2 segment that is so short (say, half a meter between just two stations) that reflections wouldn't be a problem even without terminators. Nevertheless terminators are required. Collision detection on coaxial Ethernet works by putting your own signal on the wire (through a current source) and then checking the resulting signal voltage. The signal voltage you should be seeing depends on the fact that the cable presents a 25 ohm load. If two or more stations are transmitting, then two current sources are sourcing, the voltage will be too high, and a collision is detected. So if you leave the terminators off "because I just have two stations that are half a meter apart, and that's not long enough to worry about reflections" you'll still get "collisions" all over the place even though the reflections are close enough in time to the original signal so as to not matter from a simple distortion standpoint. So explaining the problem purely in terms of signal reflections is inadequate. Jeh (talk) 20:44, 24 October 2016 (UTC)

I see 10BASE5 doesn't explain this either. Jeh (talk) 21:00, 24 October 2016 (UTC)

Well, what actually happens is that the reflection adds, so the voltage is twice as high as it would be without reflections. For short SCSI cables, you can get away with terminating on one end, but not for coaxial ethernet. I suspect that for a short enough 10base2 cable, you could get away with two terminators at one end, and none at the other, so there would still be reflections, but also the appropriate 25 ohm load. The wavelength is 30m, so you might get away with 0.5m. I once knew someone with a three way (tee connector with branches two three different rooms) 10base2 network, installed by a supposed professional installer. It worked often enough, but sometimes was just too slow. Over terminated, you get no collision detect, but signals still might get through. Gah4 (talk) 16:09, 14 November 2016 (UTC)

I had a three terminator network once, on a customer site several hundred miles away. The building was T-shaped, which explained some of it. It worked quite, but not always, well. It was very difficult to diagnose this problem remotely! It was before cheap cable testers for one thing. Only after insisting that they checked the terminators yet again and having the exasperated answer, "yes, all three of them!" did I realise what was going on.

A further complication was their use of a proprietary "no break" connector which applied an equivalent loading to the cable of about the same as three conventional taps. Andy Dingley (talk) 17:33, 14 November 2016 (UTC)

although the underlying logic may still be present.

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

---

although the underlying logic may still be present If you mean for x86 machines, I don't ever remember built-in 10base2 ports. By the time they got around to putting ethernet on board, it was already 10baseT and even 100baseTX. Some workstations did, though. NeXTstation, which I still have, and some Sun machines. I now have a Sun3/e with its associated SCSI/ethernet board, and the latter has AUI and 10base2 ports. But many Sun systems had only AUI, or AUI/10baseT ports, in later years. Now some NIC may have had the PC wiring, but the circuits not installed. It is fairly common to build a PC board with the features of the high-end model, and not install all the components when building the low model. For 10base2, you need a DC to DC converter to isolate the transceiver. That may be the bigger cost of a 10base2 port. Gah4 (talk) 12:09, 15 January 2017 (UTC)

It's unclear what "underlying logic" is referring to. On the logic side, 10BASE2 and 10BASE-T are identical (as seen from the MAC). --Zac67 (talk) 13:38, 15 January 2017 (UTC)

I agree. I never saw a PC mobo with a built-in 10base2 port. I do have a workstation (a VAXstation) which like Gah4's Sun3/e has both AUI and 10base2. Back in the early days of PC networking I did buy quite a few ISA NICs (mostly 3com's) that had both coax and 10baseT. it would make sense that they'd sell a variant without the coax connector and leave off the other associated expensive parts, like the transformer, but use the same board - no reason not to. otoh a board with every component needed for 10base2 except the connector would make far less sense IMO (if you're going to leave off the connector, why not other stuff?). In any case the text in question was speculative and plausibly questionable, so without a reference I can't see keeping it. Jeh (talk) 15:53, 15 January 2017 (UTC)

I used loads of them with 10BASE2 connectors - but they were all small format mobos for embedded systems (mid-late 90s), not intended for desktops. Some didn't even have graphics, at a time when integrated graphics were usual.

I never saw a PC mobo with AUI on it, this was more common for workstations and by the time that PC mobos had integrated networking, AUI had gone. Andy Dingley (talk) 17:31, 15 January 2017 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Remarks

Just a couple quick remarks. This page really does need attention from someone with more knowledge of the subject than I. It definitely needs in-line citations, and some parts probably need to be removed entirely for now (there are many sections that read like a debugging manual, and are almost certainly OR). These fixes shouldn't be *too* difficult though. The other issue is this talk page -- just a reminder that Wikipedia talk pages are not forums. This is not a place to discuss your memories of the era or to give debugging advice! There are so, so many other places online for that. Talk pages are for discussion of improvement to the article, as well as discussions about sources. Please try and refrain from drifting down memory lane! MrAureliusR_Talk! 09:12, 25 February 2019 (UTC)

Sometimes discussion of memories of the era lead to article improvements. Besides... before your add here, the last edit to this page was a little over two years ago. It's hardly an ongoing problem. Jeh (talk) 10:13, 25 February 2019 (UTC)

Yes, personally, I give a lot of leeway to discussions on the talk page, giving the benefit of the doubt that they will lead to improvements. This is pretty much an article in history now, though there are likely still a few such nets running. There is no new development in 10base2 technology, and so not much new to add to the article. Gah4 (talk) 14:49, 25 February 2019 (UTC)

RG/58

In addition to CB radio, RG/58 cable is very commonly used when there is need for a coaxial cable. It is common for audio, when something better than the usual home grade cable is wanted. Pretty much everything except for video and TV antennae, which use 75 ohm RG/59. That is, common in research laboratories for connecting up a large variety of signal sources and sinks. Racks of cables with BNC connectors on them are common in research labs. (RCA connectors for audio.). Gah4 (talk) 15:01, 25 February 2019 (UTC)

Doesn't this belong on the RG58 talk page? This article isn't about the cable. However you are mistaken about audio. A lot of the "high end" cable sold for audio uses RG59 or similar with RCA connectors. I suppose they could use RG58, but I've never seen it advertised or commented on. You are correct that RG58 is common in laboratories - this is because 50 ohms is the standard internal termination impedance for a great many electronic instruments (scopes, spectrum analyzers, etc.) Jeh (talk) 16:51, 25 February 2019 (UTC)

The article says that RG58 was used, and was inexpensive (relative to some other cable), because it was used for CB radio. I suppose it was used for CB, but for a lot of other things, too. When I was young, and before all audio equipment came with the usual cables that they have now, I made my own cables with RG58 and RCA connectors, or used the ones my father made when he was younger. RG59 if you need low capacitance, for phono cables. In my father's day, Heathkit was the popular audio brand, and at the end of building your tuner or amplifier, you built your own cables. Gah4 (talk) 20:30, 25 February 2019 (UTC)

I believe "because it was used for CB radio" is quite a stretch.... but anyway, I never said one couldn't use RG58 for baseband analog audio, or that no one ever did; only that RG59 and RG59-like cable is what we commonly see offered commercially in the "high end" market. One advantage to the a/v hobbyist, I suppose, is that you can then use the same cables for analog video and for S/PDIF digital audio, where the cable impedance does matter. For 10-base-2 I don't really see a technical reason for preferring 50 ohm to 75 ohm. Certainly RG59 was very common by that time as it was in very wide use by the cable TV industry. RG58 is however thinner and a lot easier to handle - maybe that was why. Or maybe the current/voltage requirements of 75 ohm termination were less preferable to those of 50-ohm termination. Jeh (talk) 22:54, 25 February 2019 (UTC)

Originally, 10base2 used the same transceivers as 10base5, but with N to BNC adapters on each end. So it has to be the same 50 ohms as thick cable. On the other hand, the 3 Mb/s ethernet that preceded 10base5 did use 75 ohm CATV cable and CATV taps. A big limitation on cable length is the resistance of the conductor, and lower impedance has a (relatively) larger center conductor. The common RG59 has a copper plated solid steel center conductor. That works well for RF, and probably isn't bad for audio. For audio, where impedance isn't important, capacitance can be a problem for longer runs. I do remember using RG59 for phono cables, as magnetic phono cartridges aren't so low impedance. Probably also a good choice for unbalanced microphone cables. Balanced line microphones use a twinaxial cable and XLR connectors. I actually know the person who did much of the design for 10Mbit/s ethernet, and might know about 10base2. But RG58 cables with BNC connectors were already commonly available, and convenient for use, even before CB radio became popular. (And I don't remember CB commonly using BNC connectors, either.) Gah4 (talk) 01:42, 26 February 2019 (UTC)

As above, it is 50 ohms so you can use 10base5 transceivers. That leaves cables like RG174 or RG313, which might be more convenient, but loss commonly available with BNC connectors. Well, with those cables there would have been other connector choices. I suspect that N to BNC adapters were already available, where others might not have been. Gah4 (talk) 05:35, 26 February 2019 (UTC)

Balanced audio uses shielded twisted pair (or star quad cable), not twinax.

RG59 and RG6 with the copper clad steel center conductor is intended for in-wall cable TV installations, and even stringing from e.g. pole to house, where high tensile strength is necessary (and poor LF performance doesn't matter). It is probably "common" because it is cheap. But the RG59 that's used for baseband audio and video is almost always solid copper center. Same for the RG58 used for 10base2, ideally. ::::: A lot of people went out and bought cheap RG58 to build their 10base2 networks and couldn't figure out why their networks were unreliable at segment lengths, etc., far below what should have worked, and the use of the copper-clad steel core RG58 was a primary reason.

It's true that transceivers for 10base5 "will work" with RG58. You could even take the N-type terminator off of one end of your 10base5 (RG8) cable run, attach an N-to-BNC adapter, and run the rest of your line with RG58. But I never saw them sold for that. In fact, all the 10base5 transceivers I ever saw had no connectors, not N, not BNC - they used a "vampire tap" arrangement. This was "convenient" in that it let you add another transceiver to your cable run without interrupting service. But not exactly possible to use with RG58! (The hole the tap made in the cable being larger than RG58's outer jacket... 10base2 had its own transceivers with a BNC female connector, far smaller (and cheaper!) than the ones made for -5. Perhaps you meant that they used compatible electrical interfaces. Jeh (talk) 07:46, 26 February 2019 (UTC)

This was the early days, before the others were available. I first knew them in a network of Suns around 1986. here is a picture of one. The transceiver part is the same, but instead of the plastic part that goes on for the vampire tap, a part with N connectors on each end goes in. Then you could connect it to N connectors between cable segments. I suspect someone then found you could put N to BNC connectors on, and invented 10base2 that way. I believe that an insert with one BNC connector came along, but by then, nice little 10base2 transceivers came out. One time when we had 10base2 transceivers on order, and computers to use, I put two vampire taps on a piece of RG213, BNC connectors soldered on each end, and it worked for some time until the transceivers arrived. (Sun workstations that we were told came with 10base2, but didn't.) Also, you still need an AUI cable, as there isn't enough space to connect directly. Gah4 (talk) 09:27, 26 February 2019 (UTC)

I was not following this, just reviewing the changes to the article. I restored information about the basic advantages of RG58 - small, flexible, inexpensive. I think any other details should go into RG-58, not here. ~Kvng (talk) 14:29, 1 March 2019 (UTC)

Present Tense

This article seems to be written in Present Tense, but this standard was long obsolete before Wikipedia even existed. Dwedit (talk) 19:40, 31 March 2023 (UTC)

Even if obsolete, the standard and some hardware still exists. See MOS:TENSE as well. --Zac67 (talk) 22:07, 31 March 2023 (UTC)