%% Image moved here from TechnologyMarchesOn and caption selected per Image Pickin' thread:
%% http://tvtropes.org/pmwiki/posts.php?discussion=1390585120056360100
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[[caption-width-right:270:"Alright, time to play me some \\
''[[VideoGame/KingsQuest King's Que]]''... oh."]]

->''"Spies are used to dealing with cutting edge encryption and billion dollar security, but sometimes the toughest challenge is cracking something old and out of date. If you find yourself up against an old and obsolete tape drive loaded with arcane software, you can either find yourself a time machine, or admit defeat."''
-->-- '''Michael Westen''', ''Series/BurnNotice''

Our time-traveling protagonists need to recover a piece of information on a computer from our time and they end up stealing the whole laptop. The FridgeLogic asks why didn't they simply just do a file transfer? As it turns out, the future tech doesn't work with tech from our time. Even though the future technology has its roots in the technology that we have currently developed, it is not backward compatible with that of its predecessors.

This can also be applied to a post-apocalyptic future stories only if the equipment is in good condition due to RagnarokProofing. Otherwise it is merely a subversion or aversion of said Ragnarok Proofing.

Of course, when the record ''must'' be accessed, this is a job for MrFixit to rig something up to make that possible.

TruthInTelevision; somewhere along the line, certain new technologies may not be backward compatible with their older versions, because they were deemed obsolete or just not worth the extra cost. Indeed, a significant portion of early electronic archives (1970s through early '90s) are now inaccessible, or nearly became so, because the hardware or file format became too outdated.

The inversion of this, where things that ''shouldn't'' be compatible ''are'', is PlugNPlayTechnology.

!!In-Universe Examples


* ''Anime/CowboyBebop'': Spike and Jet hunt through esoteric tech shops, black markets and ancient ruins, to chase down a working Betamax VCR, which is so scarce even avid collectors don't have much hope of seeing one in their lifetime. They have a tape that supposedly holds clues to Faye's past -- how far from the past she must have come from in order to have ''anything'' recorded on Beta is the biggest clue. Ironically, when they finally do find a VCR in a derelict museum it turns out to be VHS. (Made funnier because they had their choice of [=VCRs=] in the museum, and chose the VHS because the tape slot was bigger.)
* A significant amount of the plot in ''VisualNovel/SteinsGate'' consists of the cast's struggle to obtain a very old model of computer called an [[BlandNameProduct IBN]] 5100, because it's the only piece of technology capable of undoing the AlternateTimeline they've created, due to the fact that it was used to ''create'' that timeline in the first place, using a method that wouldn't be compatible with a newer model.

* In Erico's VideoGame/MegaManX fanfic series, the Cossack-class Robot Masters are recommissioned at one point in ''Demons of the Past'' to help protect Russia. However, they prove to be incompatible with 21xx technology for their internals, so the tech/medic who was sent to do the upgrading had to cannibalize the now-useless Cossack Fortress Guardians for parts like superconductor cabling and power control components. They were also not willing to risk overloading on 21xx subtanks and stuck to their stockpile of E-Tanks from the Classic Era.
* In ''[[https://www.youtube.com/playlist?list=PL1F471B8D4250D1FA Touhou: The Cursed Tape Enters Gensokyo]]'', Yukari is unable to find a ''VHS'' compatible player in Kourindou's stock, despite the piles of forgotten "modern" digital devices he had collected from the outside world. In a humourous inversion of what happened in Cowboy Bebop, she ''does'' find a Betamax VCR instead.

[[folder: LiveActionTelevision]]
* ''Series/BurnNotice'' has this happen in the present. In one episode, Michael finds an old tape drive that a rival was after in a wall. The next episode, in a voice over, he explains that old technology is often a spy's biggest headache for just this reason, before we hear Fiona say, "Fourteen phone calls, seven data recovery experts and three hours of arm twisting to find out what's on this thing [[ShaggyDogStory and it's unreadable!]]"
* ''Series/{{Continuum}}'' plays with this. On the one hand, when Kiera arrives from 2077, her super-advanced AugmentedReality implant can't interface with 2012's internet, phones, or pretty much anything else, though she is able to use her suit to brute-force hack an ATM. On the other hand, when she arrives she accidentally contacts a TeenGenius playing in his lab--because he's in the middle of ''inventing'' the tech she's using.



* In ''VideoGame/MegaManZX'', Aile and Vent have no problems using the 20XX Energy Tanks from the Classic series, while in the Battle Network series, Lan and [=MegaMan.EXE=] have no problem exploring ancient parts of the Internet.
* A character in ''[[VideoGame/ShadowrunReturns Shadowrun: Dragonfall]]'' keeps his notes on ancient DVD-R/W recordings. You have to go on {{Fetch Quest}}s to track down an old DVD player and an analog TV with the proper inputs to connect it before you can view them.


* Averted in ''Webcomic/CommanderKitty'', where [[http://www.commanderkitty.com/2011/08/28/process-of-elimination/ Zenith can find adapters for a wide variety of present-day interface formats]]...though [[{{Robosexual}} connecting with a]] ''[[{{Robosexual}} device]]'' [[{{Robosexual}} isn't her problem.]]
* Conversed on ''Webcomic/ManlyGuysDoingManlyThings''. Another character suggests that, since the Commander is from the future he must be able to fix a modern-day computer like it's nothing. He responds by pulling out a broken abacus and demanding that the other character fix it for him. He later reveals he carries that broken abacus around everywhere he goes specifically because this conversation happens to him so often.
%%* Mocked (sort of) in [[http://www.qwantz.com/fanart/dino-untitled.png this]] piece of Webcomic/DinosaurComics Reader Art. (How is this being mocked?)

* The story of John Titor, supposedly a time traveller from the 2030s who appeared on [[Radio/CoastToCoastAM Art Bell's]] forum in 2000, revolved around this -- in the post-nuclear-war future he came from, the [[http://en.wikipedia.org/wiki/2038_problem Year 2038 problem]] had yet to be solved, and he had been dispatched to a time before the war in order to acquire an IBM 5100 for use in developing a fix.
%%* Subverted in [[http://seenonslash.com/node/4137 this]] Slashdot exchange. (Do not force people to leave the page in order to see what the example actually is.

* ''WesternAnimation/SouthPark'' has the episode where Cartman froze himself to avoid waiting for a Nintendo UsefulNotes/{{Wii}}. When he is thawed out (500 years later), he discovers that future displays aren't compatible with those of his time.
* ''WesternAnimation/BeastWars'':
** the Maximals, the descendants of the Autobots, can't use their ancestors' hardware in conjunction with that of Maximal technology. Somewhat justified in that both pieces of technology they're attempting to use in conjunction are cobbled-together, oft-patched desperation-grade junk in the first place. And, y'know, the fact that the Autobot tech they're trying to use is over ''three million years'' older than their Maximal tech and is built on a different scale
** Even the smarter Maximals can't figure out how the Ark was ''made'' in the first place.
-->'''Optimus Primal:''' "Die-cast construction. [[MythologyGag It's a lost art...]]"
* Subverted in ''WesternAnimation/DannyPhantom''. Apparently, technology in the future (or at least Skul Tech) is still eligible for Tucker's PDA to hack through. Lampshaded when Tucker declares his hacking skills are ''just that awesome'' or just very, very sad.
* Averted in the ''WesternAnimation/MegaMan'' episode "Mega X", where the eponymous future robot [[PowerCopying scans and copies]] the weapon of Snakeman, an older robot. He can improve on the originals, too, as a single shot destroys Wily's weapon. Wholly justified, as X is based on Rock's design and has a modernized version of the Weapon Copy system, so he can copy anything Rock can.
* In ''WesternAnimation/TheBatman'' episode "Artifacts", a 1000 years in the future, archaeologists discover the Batcave. Their advanced computers cannot interface with or download the Bat Computer's data. Fortunately, Batman saw this coming and etched the computer's data in binary code on titanium sheets. They are able to scan that into their computers, [[FlingALightIntoTheFuture which gives them instructions on how to defeat the ageless Mr. Freeze]].

!!Real-Life Examples
%%This is for consumer computer stuff.
* Buy a new computer? Make sure all your peripherals have drivers that are compatible with the computer's OS, or be willing to upgrade them as well. Some printers, scanners, etc. from as recently as 2010 do not have drivers that are usable by 64-bit processors.
** The biggest offender of this is, of course, the CPU and RAM. RAM sticks change layout every few years, as do CPU sockets. This seems to have become progressively faster since we hit the new 10s. For example, Socket 5 and Socket 7 are electronically compatible and you can upgrade a 486 to a Pentium while reusing the motherboard. Nowadays, upgrading the CPU will also mean replacing the motherboard. Same goes for RAM, the 72-pin slot was standard for a very long time, almost a decade. Nowadays, not so much. Chances are you may also need to upgrade to a newer RAM type when you get a new motherboard along with that new CPU.
** Averted by Linux, where support for older hardware persists far longer than Windows support. Your [=Guest95=] program for ZIP drives might no longer work on even [=WinXP=], but you can get Linux to recognize that drive, assuming you still have an LPT or SCSI port, that is.[[note]]Or you have one of the final batch of Zip drives that has the USB interface that was produced shortly before Iomega discontinued the media format. Those also have a downside (or depending on your taste, upside) of coming in colors of the rainbow because they were made to tie in to Apple's original iMac line.[[/note]]
*** Things are less rosy on the software side, though. God help you if your software uses a library or API that is considered deprecated and isn't included in any of the current distros anymore, or has some other dependency conflict (the thing that was called DLL Hell in the Windows world in the times of yore). You may end up building your own distro from scratch an interesting computer science excercise ''per se'', but not the funniest thing when you have a job to do.
** Windows 7 and beyond has compatibility for a lot of older, USB based hardware, at least those made from well-known manufacturers. It's almost to a point where the CD that comes with the peripheral contains just a PDF of the user manual and a link to the manufacturer's website.
** Windows NT based [=OSes=] are also driver compatible between major versions. Windows 2000 drivers work just fine in Windows XP (both are NT 5). Windows Vista drivers work just fine in Windows 8 (Vista to 8 is NT 6). And it works the other way, usually. Though jumping major version numbers may or may not work.
* And of course, computer expansion cards at an electronic level. Have an old [=AdLib=] or 16-bit [=SoundBlaster=] card you'd like to stick to on your new PC? Chances are, you can't because they used an old pinout called [=ISA=] (Industrial Standard Architecture) which has been largely depreciated since the late '90s and has not been found on almost all motherboards made after 2002[[note]]The exception seems to be a few specialty boards[[/note]]. Same goes for [=AGP=] (Accelerated Graphics Port) which has been displaced by [=PCI=]-Express since 2007 and cannot be found on most motherboards since 2010. And oh, God help you if you have a very old [=MCA=] (Micro-Channel Architecture) card- those were only supported by true IBM [=PCs=] for a short time in the late 80s/early 90s...
* 3 1/2 inch floppy disks are getting to this state, and 5 1/4 are pretty much already there unless you're an enthusiast. And unless you work in the military or NASA, just forget about 8-inch disks! There's a semi-apocryphal story about an old industrial computer at a Russian plant whose power is backed by [[NoodleImplements several UPS batteries concocted by resident engineers]] - because if it ever turns off, it won't be able to boot again since the 8-inch floppies with the software have long since crumbled to dust. And that would render all the (similarly outdated and incompatible) equipment it controls useless.
** Which probably only worked until [[HadToBeSharp they've jury-rigged their own 8-inch disks]] out of a plastic bag, a can of red paint and a couple of file covers to back that all up, and then cobbled together a Q-bus controller for an ATA hard drive for a more permanent solution. Floppy drives are low-tech enough that a functioning 5- or 8-inch floppy could be made out of the common office supplies (because the first ones ''were''). 3" has a moulded plastic case which is harder to imitate and may require a 3D-printer to make.
*** Physical floppy disk form factors are only half of the problem; [[https://en.wikipedia.org/wiki/Floppy_disk_variants those disks can be formatted very differently, depending on the computer.]] UsefulNotes/AppleMacintosh and [[UsefulNotes/{{Amiga}} Commodore Amiga]] computers may use the same 3 1/2" disks as most IBM-compatible [=PCs=], but your typical PC floppy drive ''will not read a Mac [=400K/800K=] or any Amiga disk without a highly specialized and expensive floppy disk controller board like the Catweasel or [[https://www.kryoflux.com/ KryoFlux]].'' In fact, the [=KryoFlux=] was developed specifically for floppy disk preservation efforts!
** And let's not even start on the larger installations from the UsefulNotes/MainframesAndMinicomputers era, which are still ambling along, held together by staples, chewing gun and duct tape, because there is NO replacement for them as in, no one even knows how they work anymore. A wildly successful career in IT could still be made on knowing your way around COBOL a 50es-vintage dinosaur of a database control language that was considered a ''torture'' to program on in its heyday, simply because it was used for a surprizing number of systems that were never upgraded since.
** Back in TheSixties some computer savvy doctors and their IT-industry friends in Massachusetts General Hospital cobbled together a database for their spare PDP-7 to help with all that paperwork and make their days somewhat easier. It was a rather clumsy and jury-rigged thing, but it turned out to be surprizingly scalable. Fifty years since, the dreaded MUMPS[[note]]Massachussetts Universal hospital MultiProgram System[[/note]] (the doctors often [[DeadpanSnarker have an evil sense of humor]]) is still going strong in a lot of high throughput systems, often running on an emulated hardware within the modern high-performance server farms.
* Even before floppy disk drives, you had ''cassette tape'' drives, particularly in the 8-bit era of home computing when floppy drives were considered a luxury item.
* Iomega Jaz and Zip disks were quite popular in their time because they were still relatively cheaper than a CD writer drive, even though they have only one sixth the storage capacity (a Zip drive as of 1997 costs US$50, a CD writer costs somewhere around US$1000, and required that the owner buy a SCSI card (unless your sound card already has one, or you use a [[UsefulNotes/AppleMacintosh Mac]], UsefulNotes/{{Amiga}} or UsefulNotes/AtariST, because even though there were already IDE CD-ROM drives, CD writers still belonged to the domain of the professional and thus only SCSI interface writers were produced). And that's before you even factor in the cost of the burning software!
** However, by 2003, cheap IDE CD writers were already available, burning software prices have fallen tremendously to the point that there are free burner software if you know where to look, and their media's costs has fallen enough to be affordable and thus displace Zip drives. It should be noted, however, that even then, Zip disks and drives were still being manufactured until at least the late 2000s- mostly to cater to musicians and certain organizations who require them for backwards compatibility or ''security by obsolescence''. Generation 3 Zip drives, the final generation of the medium, have a storage capacity of 750MB, rivaling the capacity of a CD-RW, and the external drives do have a USB 2.0 interface. However, the third generation drives have a quirk of not being able to ''write'' to first generation Zip 100 disks, only read them. Even second-generation Zip 250 drives wrote much more slowly to Zip 100 disks than a native Zip 100 drive.
* Professional tape drives are surprisingly still an aversion, somewhat. Amazingly, in this modern age, many large multinational enterprises still prefer them to removable hard drives or even [=BD-R=] (recordable Blu-Ray discs) when it comes to server backups. The fact that they're still being improved upon (with version 6 of the LTO tape cartridge specification coming out as late as December 2012 and another two planned versions in roadmap) shows that there is a serious demand for them. However, they've evolved so much that they don't look anything like the reel-to-reel of TheSixties. Much of this can be attributed to the lack of reliability on recordable disks, which often use ink that is "burned in". It doesn't help that in 2010 or so, it was discovered that pretty much every [=CD-R=] made before 2003 had a shelf life of 10 years because the ink would just rot away.
* Even standard serial ports are becoming phased out in favor of USB.
** [=USARTs=] (what serial ports are based off, basically) are widely used in embedded devices because they're simple and most embedded devices don't need that much bandwidth. It's not uncommon to find an OMAP processor (the very ones that power your smartphones) to include several [=USARTs=] that you could, more or less, plug into a PC serial port with the right connections.
** Fortunately, there are plenty of USB to serial port devices, and USB cables that act like a traditional RS-232 serial port. Emulators like [=DOSBox=] even support COM port passthrough with these adapters once configured correctly.
** Businesses complained about the lack of the "standard configuration" of the rear [=I/O=] panel, so there are a few ''modern'' motherboards out there that have a serial port and a LPT port.
** Many motherboards still ship with a serial connector on the board. However, the needed port is on a bracket that is sold separately. Ditto for parallel ports- there is a connector onboard, but the port and bracket is sold separately.
* Any storage systems that use SCSI (anything pre-SAS, but mostly SCSI II) are only still interesting to electronic musicians who prefer old-fashioned hardware samplers to running a software sample player on a computer. The same goes for just about all removable storage media that came out between the 3½" floppy and the CD-RW ([=ZIP=], various MO drives, etc.). It helps a lot that musical instrument manufacturers like Akai or Kurzweil didn't change to USB and Flash memory cards as quickly as computer manufacturers.
* For the consumers, have an old PATA interface drive? Good luck finding a new motherboard that has one of those anymore. However, some companies have wised up and started offering IDE-to-SATA converters, although whether it will still allow DRM-imbued media to play is another question. Works the opposite way as well. Do you have a motherboard with a PATA interface and want to put it to good use (so you can free up that one SATA port to put in one more hard drive when all the other ports are fully occupied and there's no more free PCI or [=PCIe=] slots available)? Good luck finding a PATA optical drive. Sure, converters for PATA-to-SATA are still being made, but let's not start on the stupid DRM that may potentially block drives that go through these devices from playing protected media.
* Flash memory cards. [=SecureDigital=] is pretty much the sole remaining popular standard. [=CompactFlash=] is for semi-pro and professional photographers with [=D-SLRs=] and certain musicians, and all other formats are either for certain other musicians who still didn't upgrade to the latest music workstations and acquire second-hand memory cards from [=eBay=] instead, or defunct altogether. Card readers that support all those special formats are either using the sheer number of supported standards as a selling point ("Supports 60+ memory card formats!"), or going extinct in favor of USB devices which only accept SD and MMC anymore.
* Averted with [[UsefulNotes/MicrosoftWindows Windows]] XP. With the right amount of programming, you can run anything on it.
** Windows in general has great backwards compatibility ''provided that the program only relied on Windows provided libraries.'' It was found programs that came with Windows 2.0 still work in the 32-Bit editions of Windows 7. Microsoft even has a subdivision dedicated to maintaining compatibility, with an entire subsystem in the OS that effectively patches select programs at runtime so they can "fix" older software on customer demand. Raymond Chen, a member of that subdivision, has a lot to tell about what that is like in his blog, [[https://blogs.msdn.microsoft.com/oldnewthing The Old New Thing]].
** Some DOS games simply dislike running in Windows' protected memory spaces, while others require DOS components not found in versions of Windows released after ME. Most of this was caused by Microsoft leaving MS-DOS behind when they made the jump to Windows 2000 by using the Windows NT system structure, as all previous versions of Windows have had some reliance on DOS components.
*** Unfortunately, a lot of games coded for Windows [=95/98/ME=] simply do not work well, or even ''at all'' on Windows NT and its descendants - 2000, XP, Vista, and everything afterward. Since virtual machine software does not virtualize or emulate Windows 9x effectively, often omitting hardware graphics and sound acceleration required to run these games effectively, it has become a recent practice to make retrogaming PC builds with period-appropriate components to natively boot Windows 98 SE solely to run these games that modern computers cannot.
* Synthesizers becoming uncommon features on computers as modern games move towards sampled music (read: MP3/OGG-Vorbis/AAC) and the CPU chips become powerful enough to be able to decode these formats with little effort. It also offers two side effects, one positive and another negative. The positive? The music is now conformant and sounds the same across all hardware [[note]]in the old days, the varying amount of synthesizer chips in the market, ranging from Yamaha's OPL to Roland's MT-32, Gravis' Ultrasound and Creative's AWE, meant that music would sound different depending on which synth chip was used. Using sampled music sidesteps the issue since wave data is always reproduced the same way[[/note]]. The negative? Well, most old games require a synthesizer chip for music, so the absence of one in modern hardware means that said games are unable to play back music.
** Additionally, while Windows ships with a software synthesizer that crudely emulates a Roland Sound Canvas (proper MT-32 emulation requires [[https://sourceforge.net/projects/munt/ Munt]] and a copy of the MT-32's ROM files), few sound cards now come with a hardware synthesizer - even Creative's more recent consumer-oriented cards lack them, preferring software-based synthesizers, and they're absent from onboard sound solutions entirely. You'll only find hardware synthesizers on prosumer-oriented cards like the E-MU series now.
* Windows 7 Pro's XP Mode can work with games that don't rely on hardware graphics and sound acceleration. It was more or less intended for companies to use their office applications.
* 16-bit applications do not work in 64-bit operating systems, which are now standard in a time when 4 GB of RAM is seen as low-end and even ''smartphones'' have moved to 6 GB.
* If a pre-[=Win2000=] (especially DOS-based) game had Redbook audio, such as ''VideoGame/{{Descent}} II'', it often required an analog audio cable directly connected to the soundcard from the disc drive, as opposed to the digital playback of later Windows versions. Fortunately, the ''[=D2X=] Rebirth'' sourceport/frontend for ''Descent II'' allows the CD music to be played digitally, and ''VideoGame/{{Turok}} 2'' has a patch for the same purpose.
* The [=DirectSound=] 3D [=API=], through which games utilized hardware accelerated [=DSPs=] on sound cards to ease the burden on the CPU, as well as [=A3D=] and EAX effects for additional immersion. It's notable in that it presents game audio as 3D coordinate sources and lets the audio device mix them accordingly ''decades before Dolby Atmos did it.'' The API was heavily used in many games, including ''[[VideoGame/{{Fallout3}} Fallout 3]]''. Microsoft removed said API in Windows Vista and later, causing broken BGM playback that had so many riled up. Third party companies did try to put out fixes for it, with varying levels of success (Creative's [=ALchemy=] wrapper for the [=OpenAL=] API worked like a charm, but unfortunately this requires the gamer to own a Creative X-Fi or newer card, and have that as the active card when the fix is run; Realtek's 3D [=SoundBack=] did not work for ''Fallout 3'' at all). Bethesda Softworks' response to the complaints? Silence, which is especially painful since ''Fallout 3'' came out after Windows Vista hit the market! Admittedly, you can reinstate this feature back into Windows 8 and 10 via the Windows Programs and Features configuration in Control Panel, although it is not enabled by default due to being a legacy feature. Plus, the version shipped with Windows 7 through 10 is bugged, and does not handle MP3 playback gracefully- it only made Fallout 3 change from ''no music'' to ''broken, choppy music''.
** It can also be argued that Microsoft deprecating [=DS3D=] in favor of their new [=XAudio2=] API caused a major regression in PC gaming audio as a whole, as while a software-mixed approach like [=XAudio2=] sounds identical between systems, it does not present 3D audio coordinates for sound effects, only 7.1 surround speaker positions. Fans of HRTF-based headphone audio like Aureal [=A3D=] were not pleased in the slightest, as this made for less accurate positional cues.
* [[UsefulNotes/{{Unix}} Linux]] is said to offer great support for older hardware. But beware if you want to compile an old program which requires a version of a library or a (often third party) kernel module which is not available anymore or does not compile due to various header location changes.
** Running old audio software, for example, has grown complicated since OSS was displaced by ALSA, and when ALSA was upgraded to version 0.9, programs written for ALSA 0.5 ceased working due to extreme changes to the fundamental API calls (although understandably, many programs that was written to support ALSA 0.5 also supports OSS due to it being understood that ALSA 0.5 is experimental and should not be fully relied on alone). However, ALSA does provide a library that provides backwards compatibility with OSS, but whether the Linux distro will ship with it or not depends on the distro's communuity.
** Another comparison: [=PulseAudio=] to the ''Enlightenment Sound Daemon'', the latter which was heavily used in GNOME 1.x but was superseded by the former in GNOME 2.x and is now largely forgotten, although true to the Linux spirit, [=PulseAudio=] has an Enlightenment Sound Daemon compatibility layer- whether the Linux distribution chooses to ship with it or not is another matter...
** The same goes for graphics libraries. Since the launch of KDE 4, [=Qt3=] has mostly been phased out and is only kept in repositories for a few older applications. The same might quite likely happen with [=GTK+ 2=] when Gnome 3 starts to spread. However, the switch to GTK+ 3 will most likely take longer since GTK+ 2 is still being used in the MATE and XFCE desktop environments, and effort to move them to GTK+ 3 is happening slower than expected.
** The same also applies for ''sound'' in KDE. Many [=pre-KDE4=] apps use the ''[=aRts=]'' API, which has since been superseded by ''Phonon'' in KDE 4.x
** And then there's ''printing''. Many modern distros have switched to the Apple-created CUPS (''Common UsefulNotes/{{UNIX}} Printing System'') since around 2008. Up until 2002, they still ran on the BSD-Licensed LPR (''[=Line PRinter daemon=]''). Good luck trying to print from an early version of ''[=StarOffice=]'', if you managed to get that running. Though to be fair, CUPS does come with a LPR emulator as well for backwards compatibility (like other Linux packages mentioned here). However, again it's up to the distribution creators on whether the distribution will ship with it included and/or enabled.
** Amusingly, Windows' own backwards compatibility has proven to be a boon for the [[https://www.winehq.org/ Wine project]], which is an attempt to backwards-engineer the Windows API in order to let programs written for Windows run on Linux. Ironically, some older programs written for Windows 95, 98, or XP run just fine through Wine even though newer versions of Windows flat-out refuse to run them at all.
* Apple's never particularly cared much for compatibility. Old-school Mac users remember the [[UsefulNotes/MacOS System 7]] debacle. Macs since 2005 are no longer compatible with pre-OS X software (due to the switch to Intel processors causing the Classic environment to become no longer available); it's also now at the point where a lot of software is ''only'' compatible with these Macs, leaving older ones out of the loop. As of Mac OS X 10.7 Lion, [=PowerPC=] applications are no longer compatible either, even if they support Mac OS X, due to the abandonment of Rosetta.
** Much kerfuffle came out when Apple announced the iPhone 5 replaced the standard 30-pin dock connector introduced on the 3rd-generation [=iPod=], invalidating all of your accessories. Apple loves the future. Or at least being able to re-sell you hardware you already own.
*** Anyone who remembers the significance of the original [=iMac=] also remembers that it singlehandedly did away with ADB, SCSI, RS-422 serial, and floppy drives all at once in favor of this new but little-used port at the time: '''USB.''' Cue masses of USB adapters to legacy interfaces and USB floppy drives, though note the point above about floppy disk formats: ''USB floppy drives will not read Mac [=400K/800K=] disks.''
*** Apple did it once again with a new [=MacBook=] iteration, which has only two ports: a new USB Type-C port that is versatile but physically incompatible with existing USB Type-A connectors without the use of adapters, and the standard [=3.5mm=] TRRS headset jack. Then you have the [=iPhone=] 7, which specifically does away with said headset jack, instead opting to include a Lightning to [=3.5mm=] adapter (hope you don't like listening to a phone you're trying to charge at the same time!), and it comes with a Lightning to USB Type-A cable, resulting in the rather ironic product lineup of a Mac and an [=iPhone=] that cannot connect to each other out of the box without the purchase of additional cable adapters.
*** The new [=MacBook=] Pro lineup also goes all in on USB Type-C, with four such ports now additionally boasting support for the Thunderbolt 3.0 protocol. However, this still doesn't make the adapter dongle situation any less of a pain.
** Many have retired their first generation iPad ''out of force'' because Apple won't upgrade it beyond iOS 5.1.1, and many existing apps eventually started requiring iOS6 or newer to run. This is particularly true for web-dependent applications. One prime example is the [=YouTube=] client on these iPads will no longer work. And it's beginning to repeat itself, several newer programs are starting to require a 64-bit processor and will not run on anything older than an iPad Air 2.
** In addition to rejecting UsefulNotes/BluRay, Apple appears to be phasing out removable disc drives altogether, as few if any of their modern devices use them. This even harkens back to the original iMac in 1998 with the rejection of the floppy drive, which was still an essential media in the business and education world at the time. [[note]]For security reasons many IT departments were deathly afraid of the USB port and many workplaces and computer labs at universities and colleges had the ports on the computers disabled.[[/note]]
** Apple also removed the support for floppy drives and the Wings video capture from Macs that have them if one were to upgrade to OS X. The former actually sparked development of a homebrew driver to re-enable the floppy drive, showing how important the floppy drive was at that time. The latter was not worked on.
** Apple also does this with early versions of Mac OS X. For example, blocking a Power Mac 9600 from running even the initial OS X 10.1 release officially despite OS X having been internally developed to run on the [=PowerPC=] 604 CPU (and that's not even factoring in third-party G3 and G4 upgrades!), or a Beige G3 from upgrading to OS X 10.3 or newer despite a machine that has been upgraded to the hilt being capable of running said OS version fine. Using third party software to force install OS X 10.3 or newer on said upgraded Macs shows that it can be done. Apple probably just wants you to throw away the pre-Jobs Beige for a machine from the post-Jobs era.
** And the latest kerfuffle? Any device upgraded to [=iOS=] 11 ''loses support for 32-bit applications''. Yes, this includes apps you paid for and the developer has since disappeared or declared the app obsolete. You'll never be able to run the first [[WesternAnimation/DanielTigersNeighborhood Daniel Tiger]] app on the new iPad since the developer has declared it obsolete since ''2012'', nor can you run the earlier WesternAnimation/SpotTheDog apps or the Franchise/LeapFrog Scout apps (none of which have been in maintenance for a very long time).
* The Python Software Foundation gives updates for both Python 2 and Python 3 because many people have enormous numbers of module libraries for Python 2...that won't work on the non-backwards compatible Python 3.
* iTunes has issues with Windows XP x64; both the 32 and 64 bit versions require editing the MSI files via Orca to install and may not fully function, and the "64 64" version doesn't work with certain older video cards.
* Console and hardware emulators are fully software reimplementations of the precise behavior of old hardware, with the express purpose of allowing games and software only compatible with those old machines to be run and used on modern and relatively arbitrary hardware.
* This nearly doomed the [[https://en.wikipedia.org/wiki/BBC_Domesday_Project BBC Domesday Project]] to unreadability, as, in 2002, they realized that drives able to read the disks the project was written on were getting exceedingly rare, as ones that were compatible with the format hadn't been made in years. Fortunately, they managed to create a new system simply to read and preserve all the data on the disks.

[[folder:Video Games]]
* The major reason why backwards compatibility is hard to come by in consoles is that the manufacturer chooses a different hardware platform each generation and can't find a way to recycle the old hardware (if they can still use it). Software emulation could make up for it, but this gets harder to implement as features get more rich. As for why they choose different hardware, they feel that certain parts fit the needs of their console better than others in terms of performance and cost. Another issue that isn't brought up as much is that some older software could react badly with the current system software/OS or hardware in unpredictable ways. Support costs to ensure that all titles work on it outweighs its benefits, especially for a dwindling user base. Not to mention, since profits generally come from software sales, they're not going to make much money supporting backwards compatibility since the games were most likely already purchased for the previous hardware.
* As the Eighth Generation completely ditched composite & component in favor of exclusively using [=HDMI=], you won't be playing your Eighth Generation console on an old school [=CRT=] television (at least natively, there are special adapters that bridge the gap).

[[AC: Nintendo Consoles]]
* Unfortunately for owners of the UsefulNotes/NintendoDS, the different chipset in use means that their old UsefulNotes/GameBoy titles won't work with their new systems. Game Boy ''Advance'' cartridges, however, will still work with the DS "Phat" and DS Lite models.
* The UsefulNotes/{{Wii}}, however, is not only capable of using a lot of the [[UsefulNotes/NintendoGameCube GameCube]]'s games, but can even utilize some of the [=GameCube=]'s peripherals (like the microphone and the [[UsefulNotes/GameBoyAdvance GBA]]-[=GameCube=] link cable). However, support for [=GameCube=] peripherals and games were dropped entirely from a new "Family Pack" model introduced in late-2011.
* The UsefulNotes/WiiU retains backwards compatibility with UsefulNotes/{{Wii}} games and controllers, but lacks the ability to play [=GameCube=] discs.
* The UsefulNotes/NintendoSwitch has a different cartridge slot from the DS and 3DS family, preventing you from running older games on it that way. However, it ''does'' retain the Virtual Console ecosystem.

[[AC: Sony Consoles]]
* On the Creator/{{Sony}} side of things, the UsefulNotes/PlayStation2 avoids this, as it has actual hardware capable of running [=PS1=] games inside for the most part. ''VideoGame/{{Gradius}} Gaiden'', for instance, has a stage that runs just fine on a [=PS1=], but will slow down more than an average round of ''VideoGame/{{Espgaluda}}'' on a [=PS2=].
* While the [=PS3=] can run [=PS2=] games, it does it by software emulation, as the Cell processor is completely different from the chip set used by the [=PS2=]. There was some uproar when back in 2007, rumors abounded that certain future models of the [=PS3=] would lose this software emulation function, which they did. The first year models for the North American, Asian and Japanese markets have hardware-based backwards compatibility. The 80 GB models that came out later had software emulation for the Emotion Engine, while the Graphics Synthesizer was run on a chip. The 40 GB models and later 80 GB models dropped all BC, but there are rumors of full software emulation on all models for firmware version 3.0. Frustratingly, the European [=PS3=]'s were made with a different hardware set, and don't have any real emulation function at all.
* The UsefulNotes/PlayStation4 is unable to run games for previous Playstation consoles at all offline, [[http://kotaku.com/5985785/sonys-cloud-gaming-could-bring-new-life-to-old-games however you can stream the system's backwards compatibility with [=PS1=], [=PS2=] & [=PS3=] games to get around this]]. However, that still leaves you at the mercy of your Internet connection, and [[RegionCoding whether your region's GaiKai service has the games you want to play]].

[[AC: Microsoft Consoles]]
* The UsefulNotes/{{Xbox 360}} can run ''most'' of [[UsefulNotes/XBox its predecessor]]'s games,[[note]]reason being because unlike Sony and Nintendo, Microsoft couldn't put the predecessor console's hardware inside the 360 due to licensing issues[[/note]] but [[http://gamer.blorge.com/2008/01/09/microsoft-winding-down-xbox-360-backwards-compatibility-updates/ Microsoft has long since ceased backwards compatibility updates]], and has discontinued Xbox Live support for those games.
* Originally, the UsefulNotes/XboxOne [[http://www.ign.com/articles/2013/05/21/xbox-one-not-backwards-compatible would not be backwards compatible with the Xbox 360,]] as it used a different kind of hardware architecture (x86-64) than the Xbox 360 ([=PowerPC=]). After [[InternetBackdraft being crucified for everything else wrong with the system]], Microsoft [[http://www.xbox.com/en-gb/xbox-one/backward-compatibility revealed that the Xbox One would get backwards compatibility with Xbox 360 titles, with certain users being inducted into a Preview program for this feature with a select number of 360 titles available, with more slated for Fall 2015.]] However, backwards compatibility with games meant for the original Xbox is still not implemented, which some feel is a major oversight given that it would be trivial to implement since not only does the Xbox One's processor has a superset of the ISA of the processor used in the original Xbox, but the OS itself is a derivative of that in the original Xbox and thus it would be trivial to get first-generation Xbox games running.

[[AC: Online Services]]
* [=MMOs=] that rely on company-owned servers, e.g. for online CopyProtection, are often doomed. When the company decide the game is no longer worth running, they'll pull the plug, and rarely does the server-side software get released to anyone else. You better hope enthusiasts managed to reverse-engineer the tech and make their own, or that game's gone for good.
** ''VideoGame/CityOfHeroes'' and ''VideoGame/CityOfVillains'' are victims of this. NCSoft just decided to pull the plug on the games, and even the team in charge of the games, Paragon Studios, weren't notified until the last minute. However, it's getting a fan remake.
** Disney's [=MMOs=]- ''VideoGame/ToontownOnline'' and ''VideoGame/PiratesOfTheCaribbeanOnline''- both shut down on September 19, 2013. Disney's excuse was that the quest-driven [=MMOs=] weren't profitable for the company anymore. While the server side of the games isn't released for obvious reasons, a group of fans are taking to writing their own server for the former. The latter remains [[TemporaryOnlineContent lost]] for now.
* Gamespy, which hosts the servers for Nintendo's WFC services for the Nintendo DS, DS Lite, and [=DSi=], has terminated the WFC services with effect from May 20, 2014. You will no longer be able to enjoy online gaming on said consoles, especially on first party titles. Meaning:
** You can no longer visit friends' towns in VideoGame/AnimalCrossing Wild World and City Folk
** One of the few still playing VideoGame/{{Tetris}} DS online? Challenging another player online is no longer possible.
** ''VideoGame/PokemonBlackAndWhite'' 1&2? No more online trading and battles. Furthermore, with the loss of the Gen V Global Link website, you can no longer visit the Dream World.
** ''VideoGame/MarioKartWii''? Online races are no more
** ''VideoGame/SuperSmashBrosBrawl''? No more online fighting!
* Nintendo has begun phasing out the Miiverse services provided for the 3DS and WiiU in preparation to launch the more involved online services for the Switch. This means, for example, that the first {{VideoGame/Splatoon}}'s grafitti system will stop working as a result.
* Gabe Newell of Creator/{{Valve|Software}} has sworn that if they ever shut down Steam, they would release a patch beforehand that removed the internet connection requirement to play games bought through Steam. However, some games still come with their own DRM. They obviously can't remove that.
* In 2014, Microsoft decided to shut down its Games For Windows Live service. While this was decidedly a good thing because how of how terrible the service was, it meant that if the game used it for DRM services, you won't be able to play it. Thankfully, many of those titles that used it that were available on Steam are switching to using Steam instead. But those that weren't released on Steam or the publisher just doesn't care, those games are forever unplayable[[note]]unless worked around with a GFWL bypass DLL[[/note]]
** ''VideoGame/BlazBlueCalamityTrigger'' was re-released on Steam and GOG, but the netplay code (a must in a modern FightingGame) still tries to connect to the defunct GFWL servers.
** ''VideoGame/{{Fallout 3}}'' also makes use of GFWL as a secondary copy-protection system. Depending on the version of the game of you have, either it just won't save to cloud, or it won't run at all until said GFWL bypass DLL is installed. There is, however, a more serious issue under Windows 10- installing GFWL has the potential of bricking Windows 10's networking stack, and the game will always install GFWL as part of its installation routine. Luckily, uninstalling the copy of GFWL will solve the issue. Fallout 3 also has a problem with its radio music on Windows Vista and newer, but it can be fixed with mods- assuming you're okay with spending a whole day making the mod yourself from instructions provided online, as pre-made mods uploaded online are always [=DMCAed=] by Bethesda and/or the RIAA several hours after being uploaded, for containing copyrighted music (the mod involves recoding the MP3s in the game to AAC or Vorbis due to the issue being [=DirectSound's=] MP3 decoding and streaming ability being deprecated and the legacy provider being bugged on Windows Vista and newer systems, and recoding audio formats can take a long time on slower computers).
** ''VideoGame/GrandTheftAutoIV'' is a more egregious example of GFWL abuse - without GFWL, you can't save games, period. Thankfully, there are third party mods to fix that annoying issue. Aside from that, as like Fallout 3, the game's installer will install GFWL, which will brick the networking stack of a Windows 10 PC. Again, uninstalling GFWL immediately after installing the game fixes the issue.

[[AC: Others]]
* The Creator/{{Sega}} console line of the early Nineties were known for excellent backward compatibility (especially compared to chief rival Nintendo): the UsefulNotes/SegaMasterSystem's cartridges could not only be used on the UsefulNotes/GameGear with an adapter (not surprising as the Game Gear was essentially a portable Master System) but also on the UsefulNotes/MegaDrive with a second adapter that duplicated some of the Master System's hardware (This was partly because the UsefulNotes/MegaDrive had the same Zilog Z-80 processor that was in its 8-bit siblings). Unfortunately, incompatibility set in with future Sega consoles (oddly, given that the Mega CD and UsefulNotes/SegaSaturn used the same storage medium, the CD, and the [[UsefulNotes/SegaDreamcast Dreamcast]], while using GD-ROMS, could read [=CDs=]...). Comparing the Saturn with the Genesis, it's clear that the former shared several architectural similarities of the latter and suggests that backwards compatibility was probably planned at one point of development.
* Arcade games using the Seibu Kaihatsu COP hardware use an encryption chip so obscure that it has not been completely defeated, [[NoPlansNoPrototypeNoBackup not even by Seibu Kaihatsu themselves]]. This is the reason why quite a few games, like ''VideoGame/{{Raiden}} II'' (until recently), remain unemulatable. While a lot of the graphics encryption for a lot of COP based games have been defeated, it's been discovered that [[http://mamedev.emulab.it/haze/2012-a-year-in-mame/ the game's rules were also encrypted]], and that those encryption methods are compounded with more encryption. Thankfully some games have many ports/remakes/etc. that it doesn't really matter.
* ''VideoGame/InitialDArcadeStage 4'' doesn't allow data transfer from cards used in older versions, forcing players to make a new card from scratch. This was due to it being a complete overhaul instead of a simple upgrade.
* Although the original ''VideoGame/FarCry'' has a 64-bit upgrade patch, [[Catch22Dilemma the installer for most versions of the game doesn't work with 64-bit Windows!]] So unless you have a dual-boot option, your only choice is to install it on a machine running a 32-bit version of Windows, then copy it to the 64-bit machine.
* The VideoGame/ReaderRabbit titles had this as part of its progression- version 3 of its personalized titles dropped support for Windows 3.1 and 68k-Macs. Likewise, many of the older titles will not run on the modern Intel-based Macs due to being ''Classic Mac OS'' titles, nor would they run natively on newer 64-bit Windows [=PCs=], due to Microsoft deciding not to support 16-bit software on the 64-bit versions of Windows.
* Windows 10 and later updates to Windows 7 and 8 have ceased support for the [=SafeDisc=] and [=SecuROM=] CopyProtection schemes, so games that use these, which include most titles between 2003 and 2008, will no longer function unless either you find a legally dubious No-Disc crack, or repurchase the game without these DRM if possible.
* For a limited time, ''VideoGame/WanganMidnight Maximum Tune'' players could transfer their cars from their ''Maximum Tune 3DX+'' magnetic cards to their server-side accounts that were used for ''Maximum Tune 4''. Unfortunately, no such service was provided for ''Maximum Tune 5'' in North America (''4'' was [[NoExportForYou skipped for that region]]), forcing players to start again from scratch.

* [[UsefulNotes/{{VCR}} Betamax]]. [=AppleTalk=]. [=NetBIOS=]. SNA. DECNET. Good luck to you trying to maintain a system or workflow based on any one of those technologies; no matter how similar they may be to more successful tech, almost no one cares about backwards compatibility.
** Not to mention UsefulNotes/LaserDisc, rapidly reaching that state for cassette tapes, and if it weren't for audiophiles, the vinyl record would have surely gone that route already.
* The engineering schematics for the space vehicles used in the Apollo project were written in an early CAD/CAM application that ran on computers that no longer function. The US National Archive has all the data preserved, but have no way to read it as modern computers are incompatible with the format they are stored in & the archivists have not been able to get funding to have a conversion program written.
* This has been a significant problem for the US military as they try to upgrade their computers yet keep compatibility with tech that may be 60 years old. One case study is the schematics for the nuclear aircraft carriers, which when read were displaying dotted lines as solid and other such glitches.
* Military maps are prone to this. The [[http://en.wikipedia.org/wiki/World_Geodetic_System World Geodetic System]] is the basis for all military maps used by most modern armed forces. The modern US military and most of NATO are on WGS 84. Our allies and some countries use older versions. Units that get lost, maps that don't match, weapons and navigation systems that can't talk to each other, all adds to JurisdictionFriction.
* FOGBANK, which was an unbelievably-classified plastic used in Trident missile warheads. FOGBANK production ended in 1989. When the Navy wanted to refurbish its existing warheads, they had to build a brand-new factory to produce FOGBANK again -- and discovered that the documented procedures didn't work. It turns out FOGBANK relied on an ''[[MiraculousMalfunction impurity]]'' [[MiraculousMalfunction included in the original batch]], and this delayed the refurbishment by nearly ten years.
* Old encrypted records may become unrecoverable if the decryption methods for such messages are lost in the deeps of time. Have fun wringing out the alphanumerics of a coded World War 2 message from an obsolete tape, then decrypting it into whatever it originally said.
* In addition to all analog air signals being phased out, many cable stations are no longer watchable on analog [=TVs=] either (unless you have a box). Go buy that DTV.
* Averted at first with the move to portable music players. Many iPod buyers were thrilled that they could convert and download their CD music collection on to their new device, a factor which probably worked to speed up the adoption of MP3 players. However, with more and more [=PCs=] being sold without optical drives, and smartphones and media players becoming increasingly independent from [=PCs=], this is starting to become true.
* With DRM-encrypted music, if the DRM server goes down, the tunes are gone. Also, many iTunes songs were delisted before Apple switched to all DRM-free, so you can't upgrade them and they may never be available again. If for whatever reason, Apple decides to shut down the DRM server, you're fucked.
* Some older engines (a few cars, but mainly outboard motors for boats, lawnmower and other small engines) cannot run on gasoline containing ethanol without replacing all non-metal parts in the fuel system.
* All written languages follow this trope to a degree: ever tried reading Creator/GeoffreyChaucer in spare time, without real training? And this will eventually become true for audio recordings as well (in fact, to a much greater extent than written text for a language like English, that avoids orthography reforms like the plague).
* The one thing that people have managed to not shoot themselves in the foot: electrical connections and batteries. Thanks to international standardizations done sometime after UsefulNotes/WorldWarII, we pretty much guaranteed a plentiful supply of means to connect our gizmos to power. For example, the only thing you could possibly carry over from the original IBM PC today is its power cord. At the ultimate extreme, you only need to know the power requirements of an electrically powered device (Direct or Alternating current, which electrodes are the positive/negative or live/neutral/earth, the voltage range, current load, and so on) to figure out how to get it working.
* The distance between two rails is totally arbitrary. There are some advantages and disadvantages for a very narrow and a very wide distance between them, but ultimately the gauge, as it is called just has to be the same across a wide area, no matter which standard is chosen. Of course as most railways were built in the 19th century, sometimes explicitly with military applications in mind, non-compatible gauges were chosen ''deliberately'' in some cases. Today countries like Spain have a vast legacy network built in broad gauge[[note]]Plus, often, another more or less largue network that uses narrow gauge[[/note]] and a much smaller (but growing) network built to standard gauge (1435 mm). The latter is used almost exclusively by either tram/subway systems or high speed trains, making them non backwards compatible. There ''are'' variable gauge trains and the Spanish are among the world's leading inventors of those, but they have a lot of downsides.
* Many old websites will now have dead plugins as browsers have moved on to better software than what was once used in the early days of the WWW.
** Shockwave, replaced by Flash and, in some places, Java. And after Java was quickly discovered to be a memory hog and full of exploits, many are also jumping ship to Flash or [=HTML5=].
** [=HTML5=] standards are set to replace Flash for multimedia based applications... which is most of the reason why Flash is used. It's gaining ground, especially with big-wigs dropping Flash support.
** This is strangely averted by Wikipedia, in that a really ''old'' laptop that was using a serial port to run an ''ancient'' telephony modem (wherein you had to use an actual phone receiver in conjunction with the trunk-sized modem) with a monochrome browser-like client could load their English front page, albeit in a vastly-simplified form. There was a whole [[http://youtu.be/X9dpXHnJXaE video showing it in action]] on [=YouTube=].
** Wikipedia's aversion is mostly a side-effect of it being designed to be usable by the blind. Anything more complicated than plain text with a bit of HTML tends to give text-to-speech software fits, so the weird Flash-powered plugins and other embellishments that ''also'' wreak havoc on older browsers are verboten. Many web designers use [[http://en.wikipedia.org/wiki/Lynx_(web_browser) Lynx]] to test accessibility; if you can use a site with ''that'' and not tear your hair out, it'll work with a screen reader. [[/folder]]