13 ms·
It's a DE9, not a DB9 (but we know what you mean)
- bjourne 1y agoThis is exactly the kind of technical pedantry I keep coming back to HN for.
- dec0dedab0de 1y agoI always just called it a serial port, because I could never remember DB9 to begin with. I really hope I remember this so I can impress some nerds in the future with how pedantic I can be. (I don't know how to write that last sentence without it sounding sarcastic, but I really meant it.)
- cestith 1y agoSome other pedant might come along if you keep just calling it a serial port. They might mention that it’s specifically RS-232, and that DB-25 is also used for that. They might also mention that “serial port” could include ports for RS-422 and RS-485. They might even mention SIO and USB.
- dragontamer 1y agoAren't Cisco switches (and a large number of other switches) loaded with Serial Port / RS232 over RJ45? DB9 or DE9 isn't even the end of it. There are lots of ways to run a serial line.
- Findecanor 1y agoAre you sure those weren't using RS-232 over TCP/IP over Ethernet? That is quite common in the pro audio/video installation world, where RS-232 is common but needs extenders for longer distances. Within A/V, the norm for local RS-232 lines is actually not DE9 but 3-pin terminal blocks! (RX/TX/GND) I've seen those even on Cisco video codecs, priced $10'000+.
- dragontamer 1y agoI'm talking about this thing https://www.amazon.com/Console-Female-Serial-Ethernet-Rollover/dp/B07RZSNPLK?gQT=2 https://www.amazon.com/Console-Female-Serial-Ethernet-Rollov...
- sokoloff 1y agoI've got a bunch of Cisco switches with RJ45 connectors for the serial console ports. Here's the cable they use: https://www.bhphotovideo.com/c/product/1263972-REG/comprehensive_rj45_db9_cisco_cisco_console_cable_rj45.html/ https://www.bhphotovideo.com/c/product/1263972-REG/comprehen...
- mindslight 1y agoI've got a "Sentry Commander" remote power switch and serial server, with four 6P6C connectors for its serial ports to hook to machines and two 8P8C connectors for its own serial console and modem port. I'm sure it shipped with its own proprietary cables long since lost, but I just use RJ12 cables and those "RJ45"->DE9 modular adapters.
- numpad0 1y agoNo, most Cisco devices has an RJ45 shaped RS232C port that needs a special cable to do anything with. It's proprietary, but there's one in every networking guy's backpacks so the situation is only as bad as Lightning cable for iPhone. Most(but not all!!) networking gears that compete with Cisco uses the same cable as well.
- mikestew 1y agoIt's proprietary... Eh, depends on "proprietary", I guess. In the PLC world, using an RJ45 for a variety of serial uses is not uncommon. I've never touched a Cisco router in my life, but I've got a few things like these laying around: https://www.networktechinc.com/serial-rj45-adapters.html https://www.networktechinc.com/serial-rj45-adapters.html
- 1y ago
- alnwlsn 1y agoNull modem, crossover, DTE, DCE, straight-through, full handshaking, no handshaking, RS-232 or TTL levels. Plus CAN, RS-485, RS-422, CGA video, RGB video, and any number of industrial things use or can use the same DE9 connector (including sometimes for power).
- cestith 1y agoI haven’t touched Cisco gear in years, but that at least was true for a long time.
- icedchai 1y agoDEC equipment had something similar. A 6 pin "MMJ" connector. It almost looks like RJ45 except the clip was off center. I also remember some 90's terminal servers that had enormous "octopus" cables. There was a single connector on the box that broke out to 8 to 16-ish DB25 serial ports.
- kps 1y agoSome DEC equipment in the QBUS era also used DE9 serial ports, with a different pinout than IBM's.
- bwann 1y agoand V.35 and X.21!
- raverbashing 1y agoThe thing I don't get about this is why did people think it was a good idea to have a serial connection over DB-25? You honestly need only 3 wires. Not 25 For a Parallel port, sure 25 wires is right there. But not for a serial port
- kps 1y agoCTS, DCD, DSR, DTR, GND, PG, RI, RTR, RTS, RxD, TxD (alphabetically) makes around 11, I think.
- II2II 1y agoIf I recall correctly, the DB-25 RS-232 cables also facilitated two serial connections.
- kps 1y agoYou do. (I've never seen that used, though.)
- chillingeffect 1y agoPlus the differential versions of most of those signals for long distance doubles the number of pins. And they have optional synchronous clocks. I did some WAN work for 3Com back in the day... :)
- cestith 1y agoA few devices back in the day could be powered over DB-25 connections besides the communications, even. Some in factories might still be.
- raverbashing 1y agoYes and then we came up with soft flow control for the win
- gchadwick 1y agoI do wonder why they decided to have have separate shell size and pin designations given there appears to be a 1:1 correlation between shell sizes and pins (i.e. the 'B' shell is always 25 pins, the 'E' shell is always 9 pins). Perhaps there was plan to have fewer pins in the same shell at some point?
- elsjaako 1y agoDE15 and DA15 both exist and are pretty commonly used, I'm not aware of any other conflicts in normal versions. However, you can get weird Dsub connectors with things like COAX in there, so having the shell sizes have names can be useful.
- dfox 1y agoCoax and high-current/voltage pins are not that weird. You can also get truly weird semi-proprietary pins like fiber optics or even pneumatics/fluidics.
- deleted 1y ago[deleted]
- jones89176 1y agoit's not always 9 pins. you can get pretty creative regarding the number and type of pins (high current, coax) you can fit in that shell: DE with 2 High current contacts: https://de.wikipedia.org/wiki/D-Sub#/media/Datei:D-Sub_connectors_size_DE_with_two_high_current_contacts.jpg https://de.wikipedia.org/wiki/D-Sub#/media/Datei:D-Sub_conne... DE with 15 contacts ("VGA"): https://de.wikipedia.org/wiki/D-Sub#/media/Datei:D-SUB_DE-9-F_BLUE_VGA_IMG_1235.JPG https://de.wikipedia.org/wiki/D-Sub#/media/Datei:D-SUB_DE-9-...
- Am4TIfIsER0ppos 1y agohttps://en.wikipedia.org/wiki/File:D-Sub_connectors_size_DE_with_two_high_current_contacts.jpg https://en.wikipedia.org/wiki/File:D-Sub_connectors_size_DE_... https://en.wikipedia.org/wiki/File:D-SUB_DE-9-F_BLUE_VGA_IMG_1235.JPG https://en.wikipedia.org/wiki/File:D-SUB_DE-9-F_BLUE_VGA_IMG...
- tiahura 1y agoThe correct technical designation for a D-sub connector with nine pins is DE9. It’s early and eyes are still a little blurry, but I’m not seeing a cite? Wikipedia fleshes it out a bit: The D-sub series of connectors was introduced by Cannon in 1952.[3] Cannon's part-numbering system uses D as the prefix for the whole series, followed by one of A, B, C, D, or E denoting the shell size, followed by the number of pins or sockets No links to a primary source, but seems plausible.
- someothherguyy 1y agohttps://www.ittcannon.com/d-sub https://www.ittcannon.com/d-sub https://ittcannon.canto.com/direct/document/h10hf84e3l4n77ck3921jkrv5r/cA-7Pxp0VPt8OEnuT85_J-PeUUA/original?content-type=application%2Fpdf&name=ITT-Cannon-D-Subminiature-Product-Selection-Guide.pdf https://ittcannon.canto.com/direct/document/h10hf84e3l4n77ck...
- cwillu 1y agoDB is easier to say, and everyone knows what I mean, so I will continue to say DB9. Standards that ignore human frailties will be corrupted by humans, and that's a good thing.
- elsjaako 1y agoIt's completely clear what you mean, so DB9 is fine. In most contexts calling it a DE9 will be more confusing. If you ever find yourself wanting to order the connectors or backshells, it might be useful to know it's actually DE-9. DB15 is the only one I have issues with. The company I work with has one container with "DB15" connectors (DA-15), and one with "DB15HD" (DE-15)
- 1970-01-01 1y agoMy VGA (DE-15) and keyboard and mouse (Mini DIN #6) ports disagree. The printer port (DB-25) could not be reached for comment, as it is still set for uni-directional.
- dlcarrier 1y agoAlso, it's 8P8C, not RJ45, and sometimes it's more important to use the term from a standard body, but usually it's more important to use the term everyone knows. When documenting, I recommend saying something like this: J3 is an 8P8C jack (commonly RJ45) for IEEE P802.3bz 2.5GBASE-T communications, backward compatible with Gigabit and Fast Ethernet
- bobmcnamara 1y agoMost 8P8C other connectors are incompatible with RJ45. Why wouldn't you say RJ45?
- bigbuppo 1y agoRJ45 is a specific AT&T USOC order code to slap a normal 8P8C jack on someone's wall to provide something like multi-line analog telephone service.
- Sammi 1y agoI used to do phone support for a phone company / isp and I have no idea what you just wrote.
- SV_BubbleTime 1y agoHe said RJ45 is an AT&T part/reference number. Just like RJ11 which is your small phone plug that had 6pins, more rare.
- arghwhat 1y agoNit: RJ11 has two contacts. RJ11, RJ14 and RJ25 all used the same 6P housing though, making them 6P2C, 6P4C and 6P6C connectors, respectively. Things sold as RJ11 is often 6P4C, making for another error. The rule of thumb is that anything referred to as RJ-something is likely wrong.
- craftkiller 1y ago
- os2warpman 1y ago[flagged]
- zettabomb 1y agoDon't speak in absolutes, if you like being correct. In an engineering context, it's quite important that you know which one is which. I can and have ordered a B size shell with 9 pins. This does not look particularly similar to whatever you are imagining - there are large power pins in the shell. Because we codified the nomenclature, the difference is important, and the standard "serial port" is a DE9 and nothing else. The word "standard" wasn't codified, but D-sub connectors were.
- os2warpman 1y agoI do not think you are correct. D-subminiature connectors are codified by both IEC 60807-3 and MIL-DTL-24308K. Neither IEC 60807-3 nor MIL-DTL-24308K "standardize" or "codify" D-subminiature connectors into DA/DB/DC/DE sizes. Is there an actual standard referencing DA/DB/DC/DD/DE? It wasn't linked in the article. I do not think there is, and I think that everyone claiming that DA/DB/DC/DD/DE is a "standard" is wrong. After all, we 100% DEFINITELY want to be "correct". Words like "standard" have meaning. It appears DA/DB/DC/DD/DE is just a trade practice started by Cannon. Maybe that's why the "standardized" and "codified" specifications refer to sizes 1 through 5 (or 6). If we want the opinion of the ultimate arbiters of standardization, both Digikey and Mouser adhere to "the standard" by organizing shell sizes into IEC 60807-3 and MIL-DTL-24308K-compliant numerical sizes with letters in parentheses to denote that the letters ARE NOT a standard. The most likely reason that DA-DE sizes are not in the standards is that DA-DE were once trademarks or otherwise proprietary designations created by Cannon. Indeed, practically the only consistent and quasi-official spec sheets that list the A-E sizes are published by ITT Cannon but even they reference the actual standards (e.g. "E Size 9 (MIL-DTL-24308 Size 1)"). I assert that DA-DE are proprietary designations created by Cannon (now ITT Cannon) and calling them a "standard" is incorrect, IN AN ENGINEERING CONTEXT. In support of my position I have referenced both IEC 60807-3 and MIL-DTL-24308K and provided real-world examples from domain experts. I have also found pdfs for DIN 41652, CECC 75301-802 and referenced spec and marketing materials for Amphenol, Assmann, and Farnell/Newark and the only instances of a "standard" is when they list A-E sizes as an afterthought to aid people who are not following the actual standard to source standards-compliant parts (or ITT Cannon). What is there, besides blog posts, to show that I am not correct? edit: As a certified, triple-audited, ISO 9001-compliant weirdo, I am going to write up a nonconformity report, digitally sign it, print it out, manually sign it, then stamp it, then initial the stamp, then get it co-signed, stamped, and initialed, then scan it, then upload it into BMS, then print it out again, write the document control number on it, stamp and initial next to the document control number, have a second engineer stamp and initial it, and then hand it DIRECTLY to Quality if anyone ever refers to D-Sub connectors using non-standardized nomenclature ever again. This is serious business and we are serious engineers here.
- shermantanktop 1y agoThis is like King Canute and the tide. Technical pedantry is often interesting, as this is, and can lead to deeper understanding, though this doesn’t. But language is for communication, and the most correct language is that which communicates best. A conversation burdened with “well actually” tangents about one participant’s personal passion gets pretty tiresome.
- dogleash 1y agoBeing on the sharp edge of professional "do you want what you're asking for, or what I assume you want?" misunderstandings, you learn that it breaks in both directions often enough that sometimes not being pedantic up front isn't an option. I don't think shittalking "well actually" conversations in the context of an equipment vendor making a cutely-titled article that is very sympathetic to the inexact language around designators for products they offer is the play.
- tetha 1y agoThis is why I've learned to present people with the concrete consequences and results of their service request. Especially if I get the feeling that someone does not comprehend what they are asking for. "Your service request will result in X hours of downtime, as well as ireversible data loss between T1 and T2, and a reset of your system back to the state it was in at T1. All changes and interactions after T1 will be lost. Is this what you expect and want?" Beyond a certain amount of service disruption or monetary investment, asking twice and making sure is prudent, not pedantic.
- xp84 1y agoIn this case, is it that helpful? Since only a lunatic would want a true DB9 and no one’s ever made a giant connector with 9 pins, I fail to see the importance.
- Affric 1y agoGotta love that sharp edge. Nothing saves money like a good well actually.
- 1y ago
- deleted 1y ago[deleted]
- Findecanor 1y agoThere also existed non-standard D-subminiature connectors that didn't fit within that nomenclature. For instance, the Amiga used 23-pin connectors to connect displays and disk drives. They had the same pin spacing as DB25 but were slightly smaller.
- jgrahamc 1y agoAnd there's the infamous DB-19: https://www.bigmessowires.com/2025/06/30/bulk-lots-of-db-19s-for-sale/ https://www.bigmessowires.com/2025/06/30/bulk-lots-of-db-19s...
- 9rx 1y agoWouldn't it fit into the nomenclature with another shell type? DF, perhaps? It is not like there is any real sensibility to the naming anyway. Of the common types, DA, DB, and DC seem to follow a pattern, but DD and DE then go completely off the rails.
- 9rx 1y ago> To be blunt, the term "DB9" is plainly inaccurate because it pairs the 25-pin "B" shell with a 9-pin count, a physical contradiction. Why couldn't a DB shell house a 9 pin connector? I don't see the physical contradiction (even if nobody actually manufactures such a thing).
- relaxing 1y agoSure you could do it. You could even put 25 pins in 9 pin housing if you made the pitch smaller. They just don’t exist, and hopefully never will.
- 9rx 1y agoWhat's the physical contradiction, then? I don't get it.
- aleph_minus_one 1y agoThe physical contradiction is that the standard requires a particular pitch of the pins, and a specific distance of the pins from the shell.
- 9rx 1y agoWhat's the point of "9", then? And how do you explain DE15 (popularized by VGA)?
- khedoros1 1y ago> What's the point of "9", then? Originally? Because that was the naming convention that Cannon designated. Later, because the shell size wasn't sufficient to determine the number of pins. > And how do you explain DE15 (popularized by VGA)? Cannon's D-series connectors started with 2 rows, at the "normal density" of 326/3000 of an inch between pins. They later expanded the range of connectors with "high density" and "double density" connectors that put more pins at greater densities into the original shell sizes. DE15 is in the "high density" range.
- alnwlsn 1y agoThere's a lot of things like this, especially when the connector is commonly used for just one thing. One is "composite video" which at one point or another I have heard items on this list used interchangeably (though not always at the same time): composite video - RS-170 - monochrome video - EIA-170 - NTSC - black and white video - CVBS - B&W video - RS-170A - analog video - PAL - yellow RCA plug - just plain "video" These don't even all refer to the same thing, and some are definitely more correct than others, but all are used even by technical people. Here's another one: "Amphenol connector", "Cannon connector" or "Molex connector". It's the same as saying "Ford car".
- deathanatos 1y agoThe 1.44 MB diskette is my canonical "dear God what happened"-named thing. The traditional diskette is 1440 KiB. I.e., base-2, today named "kibibyte" though in that day that word didn't exist yet & it was just a kilobyte and the base 2 inferred from context. Clearly, someone didn't infer, and moved the decimal, so that 1.44 "MB" is 1.44 * 1000 * 1024 bytes. The actual capacity is thus either 1.41 MiB or 1.47 MB.
- hinkley 1y agoHard drives continued to make that mistake, and once you got to GB size they were overselling the disk space by an appreciable amount.
- alanfranz 1y agohard drives intentionally use giga and tera rather than gibi and tebi. They're right; it's the memory sticks that are usually wrong :-)
- chuckadams 1y agoNobody says "gibibyte" out loud without giggling or getting giggled at. I think we should start saying "gigglebyte".
- supportengineer 1y ago[flagged]
- BryanLegend 1y agoSeriously, nobody cares!
- bobsmooth 1y agoIt's not gatekeeping what are you talking about?
- brudgers 1y agoYou have been misusing the D-sub connector terminology No I haven’t and the same is true for approximately everyone else. Because we have not been using D-sub connector terminology at all. We have been talking about the things that come with (and without) DB9 connectors. We have been (mostly) playing —- as the witty Wittgenstein would say — a different language game. That’s why you know what I mean. So bring me a slab.
- deleted 1y ago[deleted]
- andix 1y agoIf you keep calling it DB9 everybody knows what you're talking about. They don't think you're weird and they also don't waste time talking about terminology.
- OhMeadhbh 1y agoWords mean things. Especially in engineering disciplines. It's perfectly fine for a product manager to say "DB9", but the guy who has to order the part from a supplier will probably want to use the correct terminology. If there's a mistake, it's the supplier's fault.
- deleted 1y ago[deleted]
- orphea 1y ago> Words mean things. I struggle with someone I work with because of this :( They might as well call a DB9/DE9 a USB connector and expect everyone to understand them. They're both connectors after all, right?
- 9rx 1y ago> If you keep calling it DB9 everybody knows what you're talking about. But might question what your wiring has to do with a 2000s-era Aston Martin.
- andix 1y agoAI image generation can finally express what I picture when hearing Aston Martin DB9: https://chatgpt.com/s/m_6883b37e1fc881919e3af8f862aa7900 https://chatgpt.com/s/m_6883b37e1fc881919e3af8f862aa7900
- yonatan8070 1y ago"DE10 isn't real, it can't hurt you"
- 1y ago
- OhMeadhbh 1y agoWe used the DD-50 connectors in the telephony world and called them "DD-50 connectors." I always wondered why they were "DD-50" and the 9 and 25 pin connectors were "DB-9" and "DB-25". Now I know... we were just using the nomenclature wrong.
- Cyan488 1y agoSparkfun should take it upon themselves to correct the centuries-old mix-up of "conventional current" next :)
- stn8188 1y agoI always thought this was really interesting. The Coast Guard's Electrician's Mate training program taught electron-flow theory, so it was tough to switch my brain to hole-flow theory when I went to college. Technically the math is the same but man it threw me off with schematics.
- userbinator 1y agoWas that in the context of vacuum tubes? There, electron flow definitely makes sense.
- DecentShoes 1y agoWhat's that?
- Cyan488 1y agoBen Franklin's coin flip landed the wrong way - nowadays electronics circuits are calculated and drawn assuming movement of positive charges, when in reality it's the negatively charged electrons that flow.
- cperciva 1y agoNothing wrong with saying that an absence of electron is moving. Both electrons and electron holes are just excitations in a quantum field anyway... ;-)
- mlyons1340 1y agoAFAIK, Electron holes refer to the P-type charge carrier in a semiconductor lattice where the absence of electrons behave similar to electrons in an N-type semiconductor. Benjamin Franklin was not concerned with solid state physics rather he's referring to the charge carrier in a conductor being positive when we later discover that its negative (electrons). When current flows through a conductor its just electrons (not holes) moving from negative to positive.
- phendrenad2 1y agoCould the name "DB9" have come from 25-pin serial ports with only the minimum 9 pins populated? That would be a correct "DB9" and would also be valid electrically. I think I've even seen one of those in the wild before.
- codazoda 1y agoInterestingly they have 25 to 9-pin adapters and the majority of DB25 devices I worked with were fine either way. So, the devices generally used 9 pins or less (or at least 9 or less pins were "important"). There are, of course, devices that use more than that, but most things seemed to use less. Maybe that's part of the reason the 9-pin became more standard.
- nick__m 1y agoFrequently only 3 pins are used in a DE-9.
- gowld 1y agoSo, the [ABCDE] in D?-N is redundant and useless, so it doesn't matter what letter you use. Humanity triumphed, eliminating useless redundancy.
- mauvehaus 1y agoNo, because a VGA port is a DE-15 and a DA-15 is used for, uh, something? ETA: Oh hey, just to make things confusing, Apple used DA-15 for video on older Macs. https://en.m.wikipedia.org/wiki/D-subminiature https://en.m.wikipedia.org/wiki/D-subminiature
- fredoralive 1y agoDA15 was used for amongst other things Mac video outputs in the beige era, PC joystick / MIDI ports and Ethernet AUI ports.
- encom 1y agoGiven that DB9 is so pervasive (and I admit this is new information to me), I thought AI training data might include the error but no, ChatGPT knows DB9 is wrong: https://chatgpt.com/share/6883b2ff-d26c-8002-bc4d-b184d7afd472 https://chatgpt.com/share/6883b2ff-d26c-8002-bc4d-b184d7afd4...
- tycoon666 1y agoWhat's about the 19 and 23 pin variant
- krs_ 1y agoSome discussion on the 19 pin variant from last year: https://news.ycombinator.com/item?id=40397593 https://news.ycombinator.com/item?id=40397593
- zettabomb 1y agoD-sub has got to be one of the longest enduring connector standards I can think of, apart from wall outlets. They're from the 50s, originally for military use, and we're still speccing them in new space hardware today. Now they've got coax/twinax, high power, fiber, and even pneumatic "contacts" if you know where to look (and can afford it). I can't say that they'd be my first choice, personally, but it's quite remarkable to see how well they've fared over the better part of a century.
- paradox460 1y agoPhone jacks. Invented in the late 19th century. Still in use today.
- zettabomb 1y agoI assume you're referring to the 1/4" jacks, not RJ series?
- EvanAnderson 1y agoI assume you're talking about these, right? https://en.wikipedia.org/wiki/Phone_connector_(audio) https://en.wikipedia.org/wiki/Phone_connector_(audio)
- bluGill 1y agoXLR used (mostly) in audio is also from the 1950s. The biggest problem with these standards is they are used for everything and so you cannot be sure that if the cable fits it will work. If a USB cable fits it will almost always work - but if it doesn't it will be obvious to your average idiot way (that is you can plug a mouse into a power supply - but nobody expects it will work). USB-C somewhat violates that, but even still it mostly is a case if you can get the connectors to fit it works.
- zettabomb 1y agoDidn't even think of that, yes of course XLR and for that matter, 1/4" TS/TRS connectors were originally for switching phones at AT&T, before automated switching. Incidentally, you can also blow up quite a bit of stuff with them, depending on whether they are at consumer "line level", pro audio "line level", or even speaker level. We're definitely too comfortable with "if it fits, it works" (or at least isn't harmful".
- ribcage 1y ago[dead]
- op00to 1y agoFrankenstein’s monster!
- rzzzt 1y agoI was looking for this one. Three angles for a potential retort: a) Frankenstein is the real monster in the book b) The monster is Victor's son, so inherits the family name and thus is also (a) Frankenstein c) A modern adaptation gives the reader explicit permission to use "Frankenstein" as the name for the monster: https://xkcd.com/1589/ https://xkcd.com/1589/
- op00to 1y agoI prefer to calm them “Frankensteins”, like: “Look out, there’s a Frankenstein to push into that lake!” But can never resist the Frankenstein’s monster pedantry, I find it hilarious.
- tekawade 1y agoThis is great. Maybe having total or stats/tools for comparison will be awesome plus. Set input and output and check cost.
- lttlrck 1y agoThe examples would illustrate the issue a little better if there were two pin counts with the same shell, eg DE9 and DE15 and maybe two shells with the same pin count (though I'm not aware of such an example). Without that it is barely worth the distinction.
- mixdup 1y agoYep, was going to comment on this aspect. If you can't have a DB-9 (which would be the large shell but with a bunch of missing pins) they should have just called the m DA-DE or D-(number of pins)
- lutusp 1y agoThis might not prevail in the world of tech, but in language studies, words mean what the majority of their users think they mean. Examples: * Decimated. How many of you know this means (or once meant) reduced by 1/10? * Literally. Often used to mean figuratively, to the degree that it can be relied on to mean nothing at all. * Reign, as in "reign him in". Clearly now an accepted misuse, reign once defined what a monarch does to a kingdom, not what a cowboy does to a horse (i.e. rein). * Fewer / less. Sadly interchangeable in modern writing, "fewer" was once reserved for enumerable things, while "less" referred to continuous measures. Less water, fewer liters of water. * Double precision. In computer science, defined in IEEE 754 as a floating-point data format with a 53-bit mantissa, therefore 15.95 decimal digits (53 * log(2)/log(10)). Now the norm, the default, to the degree that people may forget what "double" refers to. Because of double's ubiquity, in the fullness of time I expect single precision will come to be known as ... wait for it ... half precision. Lexicographers are at pains to point out that words mean what people think they mean. I think they have a point.
- owenfi 1y agohttps://connectorbook.com/identification.html?N=&n=d_sub_conn&c=DE-09 https://connectorbook.com/identification.html?N=&n=d_sub_con... See the online interactive adjuncts here: https://connectorbook.com https://connectorbook.com
- pimlottc 1y agoDB25 and DB9? Oh, you mean parallel port and serial port? :)
- fhars 1y agoDB-25 is the standard RS-232 connector. DE9 is just the cheap alternative for cases where you don't need all control lines
- HarHarVeryFunny 1y agoDoesn't a DB9 connector include all the DB25 RS-232 handshaking lines, even if not all devices actually use them? I grew up in the 70s-80s with serial connectors and a drawer full of cables, DB25-DB9 adaptors, gender-benders, null modems, breakout boxes, etc, and the only (very common) source of incompatibility that I can recall was connecting devices where one side wanted hardware handshaking but the other didn't provide it, so having to make custom cables with handshaking tied hi/lo to fake it. Some devices used software XON/XOFF handshaking, so for example on a typical terminal, depending on what you were connected to, you could pause text being sent to the terminal with XOFF (Ctrl-Q), and resume with XON (Ctrl-S). I've got a softspot for serial communications - used be more a source of fun rather than frustration to dip into the draw of cables/etc and get two devices happily talking to each other.
- ac29 1y ago> Doesn't a DB9 connector include all the DB25 RS-232 handshaking lines Handshaking yes, but not all potential RS232 signals, of which there are 11. I work with RS232 frequently and even CTS/RTS is rare to use. Never personally seen anything use DTR, DCD, DSR, or RI though I know they did see historical use.
- HocusLocus 1y agoThe real reason is that in the 1980s this illustration ( https://cdn.sparkfun.com/assets/home_page_posts/1/4/2/9/8/DSubminiatures.png https://cdn.sparkfun.com/assets/home_page_posts/1/4/2/9/8/DS... ) was not shown to people. And an illustrator, probably who hadn't seen it either, is who got it wrong. I don't blame them. The existence of an arbitrary letter invariably joined with a useful and descriptive number is the fault here. And the illustrator could NOT show the whole thing anyway because it contained diagrams of products not sold. The perfect setup. That is all. Everything else is blah blah blah (about DB9, love all the examples of other goofy identifiers!) People strive for accuracy and remember things. I love people-in-general and they have an impressive track record. They improved on the standards committee.
- HarHarVeryFunny 1y agoIMO this is a case where being correct causes confusion rather than clarity. Everyone calls this connector DB9, so calling it DE9 is going to make people wonder if it's really a DB9 or only looks like it ...
- tssva 1y agoMaybe next they can work on getting people to stop calling Category 3 - 8 cables Ethernet cables.
- TomWhitwell 1y agoA favourite paper: “ A Microfluidic D-subminiature Connector” “ Standardized, affordable, user-friendly world-to-chip interfaces represent one of the major barriers to the adoption of microfluidics. We present a connector system for plug-and-play interfacing of microfluidic devices to multiple input and output lines.” https://pmc.ncbi.nlm.nih.gov/articles/PMC3786702/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3786702/ Previous discussion: https://news.ycombinator.com/item?id=32886596 https://news.ycombinator.com/item?id=32886596
- overgard 1y agoWell, I admire the nerd logic, but it seems like it would just unnecessarily cripple sales if people searching for it under the common name can't find it.
- androiddrew 1y agoI love these sparkfun boards. I built this little web app just to be able to play with them in the browser too https://webserialconsole.com/ https://webserialconsole.com/
- sneak 1y agoIf everyone calls something by a name, that's its name, whether you like it or not. "ask" is now also a noun. I spent years wishing (and pretending) that this wasn't the case, but you can't fight the wind.
- chillingeffect 1y agoWhile we're at it, RS-232 is not serial. It's a voltage specification.
- Arrowmaster 1y agoBut it is kinda important to know if something is using TTL or RS-232 voltages before connecting to it. Using the wrong one might let the magic smoke out.
- nailer 1y ago9 pin D connector sounds clearer, and doesn’t waste a letter. D9 works for the same reason.
- noobermin 1y agoOne of the more confusing versions of this I came in contact with recently is the 23 pin amiga rgb port. It has no real official D-subminature name as there is no such designation for the shell of a 12+11 pin port, which I assume is due to the fact that it was for a non-IBM machine...BUT some sellers (on aliexpress) DO call it a DB-23 port...I did figure it out eventually and got a few but it did take a while after searching for "12+11 serial" and being a bit frustrated at not finding anything.
- eggsome 1y agoSurprised that no one has corrected them that it's not RS232 anymore. It was eventually ratified and it's technically called EIA-232-F (at least for the most recent 1997 version).
- djaychela 1y agoFor me, if I ever say IEC mains lead I get a blank expression. C13 even more so. "Kettle lead" (Which is notched to indicate it can take a higher temperature and most of cables aren't that, they will be the c13 type), and their face lights up and a cable will be handed to me. Just one of those things that's wrong, but it's not worth being pedantic over it, imo.
- dingaling 1y agoGiven the paucity of electric kettles in the USA, I wonder how that term became so widespread. Ironically in Europe where the IEC cables were familiar from kettles, they've largely been superceded by cables hardwired into a base pad onto which the kettle is set.
- indrora 1y agoBritish English, most likely.
- geokon 1y agoWhy are almost all data connectors designed with male/female pairings and not a unisex connection? (like half the contacts pins are half are slits and you can plug any cable in)
- mark-r 1y agoI take issue with referring to the DB-25 as the connector you'd see for old parallel ports. I'm old enough to remember when the DB-25 was universally used for RS-232 serial ports, and parallel used an oddball larger Centronics connector.