History Main / NoBackwardsCompatibilityInTheFuture

* 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 ''[[VisualNovel/MaxsBigBustACaptainNekoraiTale Max's Big Bust 2: Max's Bigger Bust]]'', after you arrest [[spoiler:Hector Von Haus]] for [[ItMakesSenseInContext trying to open up a Frakk]], Ellie and Aisha try to hack his computer for his emails, since Max couldn't use the USB stick intended for that purpose, seeing as the computer is 1994 vintage. The problem, along with the whole 1994 vintage thing, is that it uses an obscure proprietary OS made by a small (and long since bankrupt) Australian tech company in the 90s with a source code described as "notoriously difficult to work with." They have to source another computer of the same model to develop a hack they can use to get in without losing the data.

Let's think about that for a moment. In the 1970s through the 1980s, the common forms of data storage for mainframes and minicomputers were 1/2", 1200' magtape reels (capacity about 60MB), and punched cards (96 bytes on the IBM S/38 card, 80 bytes on the standard Hollerith card). Minicomputers and microcomputers might use paper tape or 8" floppy discs. ''None of these are readable today'' by most equipment. In the 1980s-1990s, the 5 1/2" floppy disc and the 3 1/2 inch hard shell floppy were popular. Today, computers do not have floppy drives. And there was the Zip disc around 1995-2000, which was readable/writable either by an external drive or you could buy one to install like an extra floppy disc. Nobody uses Zip discs any more. Heck, most computers these days don't even have optical drives, and that's a form of physical media format that is ''still being used''.

* In ''VisualNovel/MaxsBigBustACaptainNekoraiTale Max's Big Bust 2: Max's Bigger Bust]]'', after you arrest [[spoiler:Hector Von Haus]] for [[ItMakesSenseInContext trying to open up a Frakk]], Ellie and Aisha try to hack his computer for his emails, since Max couldn't use the USB stick intended for that purpose, seeing as the computer is 1994 vintage. The problem, along with the whole 1994 vintage thing, is that it uses an obscure proprietary OS made by a small (and long since bankrupt) Australian tech company in the 90s with a source code described as "notoriously difficult to work with." They have to source another computer of the same model to develop a hack they can use to get in without losing the data.

%% Image moved here from TechnologyMarchesOn and caption selected per Image Pickin' thread:
%% https://tvtropes.org/pmwiki/posts.php?discussion=1390585120056360100
%% Please do not replace or remove without starting a new thread.

[[folder:Anime]]

[[folder:Fanfiction]]

[[folder:LiveActionTelevision]]

[[folder:VideoGames]]

[[folder:WebOriginal]]

[[folder:WesternAnimation]]
* ''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.[[note]]This doubles as HilariousInHindsight, as by the end of the 2010s, you'd be hard pressed to find a TV with component inputs that could take full advantage of the Wii's video output, and lower-end [=TVs=] had even ceased to have composite inputs.[[/note]]

* 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]].

* This used to be the case, along with RockBeatsLaser, in ''WebOriginal/OrionsArm''. For example, different colony ships (launched decades or even centuries apart) would experience incompatibilities in their information systems, propulsion systems and docking equipment, and sometimes even their environmental requirements and genetics. [[https://www.orionsarm.com/eg-article/57739a893df5c The Compatibility Protocol]] was created to avert this.

Let's think about that for a moment. In the 1970s through the 1980s, the common forms of data storage for mainframes and minicomputers were 1/2", 1200' magtape reels (capacity about 60MB), and punched cards (96 bytes on the IBM S/38 card, 80 bytes on the standard Hollerith card). Minicomputers and microcomputers might use paper tape or 8" floppy discs. ''None of these are readable today'' by most equipment. In the 1980s-1990s, the 5 1/2" floppy disc and the 3 1/2 inch hard shell floppy were popular. Today, most computers do not have floppy drives. Many don't even have optical drives. And there was the Zip disc around 1995-2000, which was readable/writable either by an external drive or you could buy one to install like an extra floppy disc. Nobody uses Zip discs any more.

Now let's go backwards. Today, in the 21st Century, if you have to move a medium-sized file, say a 2GB 10-minute video from one computer to another, what would you do? Copy it over the internet or onto an SD card or external hard disk. But let's say you wanted to take that video into the past and make it widely available. Prior to about 1995 access to the Internet was rare, and slow (most people at best had modems at 14.4kbps while the few poorer folks were still stuck at 9.6kbps, and a "broadband" 128kbps ISDN internet connection cost several hundred dollars a month. Cable internet, which promised supreme speed, was still in development at the time). Copy it from your external hard drive, jump drive, or SD card and adapter? Prior to 1998 Windows did not support USB and even then it wasn't reliable. But let's say you figure a way to connect your device, how do you copy it then? Copy it to or from flash media? Prior to about 2004, the most common form of flash-type external device was [=SmartMedia=], and the maximum size was a whopping 128 meg. [=SD=] cards didn't exist then, writable CD drives (capacity 500MB) were available, but (writable) DVD drives weren't.

Now, this is just what has happened over about the last 45 years: 1975 until now. Imagine the changes over a hundred or two hundred years. Needless to say, this trope is 100% TruthInTelevision.

Now, this is just what has happened over about the last 45 years: 1975 until now. Imagine the changes over a hundred or two hundred years.

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.

* ''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.[[note]]HilariousInHindsight, as even as of 2022, you'd be hard pressed to find a TV with component inputs that could take full advantage of the Wii's video output. Some [=TVs=] don't even offer composite input anymore and instead only has an antenna receptacle and three to four HDMI ports, and maybe one or two [=DisplayPorts=].[[/note]]

[[folder:FanFiction]]

%%* Mocked (sort of) in [[http://www.qwantz.com/fanart/dino-untitled.png this]] piece of Webcomic/DinosaurComics Reader Art. (How is this being mocked?)

* 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.

* ''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.[[note]]HilariousInHindsight, as even as of 2022, you'd be hard pressed to find a TV with component inputs that could take full advantage of the Wii's video output. Soe TVs don't even offer a composite input anymore and instead only has an antenna receptacle and three to four HDMI ports, and maybe one or two [=DisplayPorts=].[[/note]]

* ''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.[[note]]HilarousInHindsight, as even as of 2022, you'd be hard pressed to find a TV with component inputs that could take full advantage of the Wii's video output. Soe TVs don't even offer a composite input anymore and instead only has an antenna receptacle and three to four HDMI ports, and maybe one or two [=DisplayPorts=].[[/note]]

* ''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.

Now let's go backwards. Today, in the 21st Century, if you have to move a medium-sized file, say a 2GB 10-minute video from one computer to another, what would you do? Copy it over the internet or onto an SD card or external hard disk. But let's say you wanted to take that video into the past and make it widely available. Prior to about 1995 access to the Internet was rare, and slow (most people at best had modems at 28.8kbps while the few poorer folks were still stuck at 14.4kbps, and a "broadband" 128kbps ISDN internet connection cost several hundred dollars a month. The few lucky ones were researchers at AOL-Time Warner who got to try out the first generation of cable modems which offered a mind blowing 10mbps). Copy it from your external hard drive, jump drive, or SD card and adapter? Prior to 1998 Windows did not support USB and even then it wasn't reliable. But let's say you figure a way to connect your device, how do you copy it then? Copy it to or from flash media? Prior to about 2004, the most common form of flash-type external device was [=SmartMedia=], and the maximum size was a whopping 128 meg. [=SD=] cards didn't exist then, writable CD drives (capacity 500MB) were available, but (writable) DVD drives weren't.

Now let's go backwards. Today, in the 21st Century, if you have to move a medium-sized file, say a 2GB 10-minute video from one computer to another, what would you do? Copy it over the internet or onto an SD card or external hard disk. But let's say you wanted to take that video into the past and make it widely available. Prior to about 1995 access to the Internet was rare, and slow (most people at best had modems at 28.8kbps, a "broadband" 128kbps ISDN internet connection cost several hundred dollars a month). Copy it from your external hard drive, jump drive, or SD card and adapter? Prior to 1998 Windows did not support USB and even then it wasn't reliable. But let's say you figure a way to connect your device, how do you copy it then? Copy it to or from flash media? Prior to about 2004, the most common form of flash-type external device was [=SmartMedia=], and the maximum size was a whopping 128 meg. [=SD=] cards didn't exist then, writable CD drives (capacity 500MB) were available, but (writable) DVD drives weren't.

Now let's go backwards. Today, in the 21st Century, if you have to move a medium-sized file, say a 2GB 10-minute video from one computer to another, what would you do? Copy it over the internet or onto an SD card or external hard disk. But let's say you wanted to take that video into the past and make it widely available. Prior to about 1995 access to the Internet was rare, and slow (most people at best had modems at 9.6K bps, a "broadband" 56K internet connection cost several hundred dollars a month). Copy it from your external hard drive, jump drive, or SD card and adapter? Prior to 1998 Windows did not support USB and even then it wasn't reliable. But let's say you figure a way to connect your device, how do you copy it then? Copy it to or from flash media? Prior to about 2004, the most common form of flash-type external device was [=SmartMedia=], and the maximum size was a whopping 128 meg. [=SD=] cards didn't exist then, writable CD drives (capacity 500MB) were available, but (writable) DVD drives weren't.

[[folder: LiveActionTelevision]]

* 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.

Let's think about that for a moment. Today, in the 21st Century, if you have to move a medium-sized file, say a 2GB 10-minute video from one computer to another, what would you do? Copy it over the network? Prior to about 1995 access to the Internet was rare, and slow (most people at best had modems at 9.6K bps, a "broadband" 56K internet connection cost several hundred dollars a month). Copy it onto an external hard drive? Prior to 1998 Windows did not support USB and even then it wasn't reliable. Copy it to or from flash media? Prior to about 2004, the most common form of flash-type external device was [=SmartMedia=], and the maximum size was a whopping 128 meg. [=SD=] cards didn't exist then, writable CD drives (capacity 500MB) were (but writable DVD drives weren't.) Now, this is just what has happened over about the last 30 years. Imagine the changes over a hundred years.

!!Real-Life Examples
[[folder:Computers]]
%%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.
** And to make things worse, Microsoft started requiring Windows drivers to be ''digitally signed'' with more recent versions of Windows 10, or they won't load. Even if your printer has 64-bit drivers (most newer printers made after 2011 do), if the company that made it refuses to put out updated drivers that are signed, you're SOL. [[note]]You can cheat by using a Raspberry Pi combined with a cocktail of Linux softwares to make the printer emulate a generic network Postscript printer if it's supported in Linux, but that is not a fun exercise to partake in when you have work to complete on a dateline[[/note]]
** 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 36-pin slot was standard for a very long time, almost a decade. The 72-pin had a shorter lifespan of 6 years. Nowadays, RAM standards seem to change every 4 years. 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 exercise ''per se'', but not that fun when you have a job to do. If the software's source code is available to you, though, you may end up patching the software until it is barely recognizable anymore instead- still not a fun thing to do when you have a job to complete on a deadline either way, but hey, you get to be known as the guy who forked an abandoned software and brought it up to date.
** 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=] (Industry 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 was probably only used until [[HadToBeSharp they 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 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 gum 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 surprising 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 surprisingly scalable. Fifty years since, the dreaded MUMPS[[note]]Massachussetts Universal hospital Multi Program 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 emulated hardware within 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. Somewhat subverted in that you can still buy a cheap tape deck in 2019- but with their cheap mechanism that introduces tons of wow and flutter, your half-hour tape loads will most likely fail half of the time.
* 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, cheap IDE CD writers were already available by 2003, burning software prices have fallen tremendously to the point that there is 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. A good example would be Gigabyte's Aorus [=B450M=] motherboard, which was released in ''2018''. Despite being designed for a second-generation AMD Zen CPU and using [=DDR4=] memory, the board still sports one Parallel and one Serial header, which you can make use of by buying the brackets from eBay- yes, companies still make the bracket as well.
* USB itself is a mixed bag:
** At the very least, you are guaranteed USB 1.x functionality, but it's reasonable to assume you'll have USB 2.0 functionality as well. If you're not sure what USB version you're dealing with, this is the safest assumption you can hold. [[labelnote:Explanation]]USB 1.1 did originally hit the markets around the time Windows [=98SE=] was the standard, but it was still relatively obscure and 2.0 was released fairly quickly after it. A greater majority of early-era USB hardware is actually USB 2.0, but 1.1 functionality is baked-in to all USB devices.[[/labelnote]]
** In general, USB standards retain full backwards compatibility in their wire layouts, and the root controllers of newer USB hardware interface just fine with older devices. The reverse is a mixed bag: Strict standards compliance means a 3.0 device CAN work with limited bandwidth in low-speed mode if it were connected to a 2.0 socket, but some less-compliant devices may not properly carry this standard. In addition, the device will try to instruct Windows to notify users that a newer device is plugged into an older, slower USB port, and will thus not function at full speed.
** The majority of Device Classes created for USB standardization were set in stone when the 2.0 standard became the effective ''lingua franca'' of most peripherals and devices, although manufacturers had to rely on some hardware/device definition trickery to "cheat" gaming keyboards into using more of the bandwidth of the USB system for ''n''-key rollover by having the computer detect the physical keyboard as ''multiple'' keyboards, so that more inputs can be read at once. [[labelnote:Explanation]][[https://en.wikipedia.org/wiki/Rollover_(key) Rollover]] refers to the number of keys that can be pressed at once and still be registered by the computer.[[/labelnote]]
** The Classic Type A head is exactly the same oblong shape throughout all the current iterations, only adding additional contacts in the 3.0 configuration. The Classic Type B 2.0 head (used in printers and on client devices like older tabletop hard drives and scanners) is forwards compatible, but the Type B 3.0 head has an extended shape that makes it not fit into older Type B sockets.
** The Mini-A and Mini-B heads were quickly depreciated in the market, only surviving in cheaper devices due to the proliferation of existing plugheads in the market for budget manufacturers.
** Micro-B 2.0, which succeeded the Mini-B heads and were designed to put plugging stress on the cable rather than the socket (and slim enough to become the industry standard for most smartphones manufactured before 2017), are forwards compatible, and Micro-B 3.0 once again has an additional section added to the side of the cable head to make room for the additional wire contacts and is not backwards compatible (and is mainly seen in a few early USB 3.0 Samsung smartphones and portable hard drives/solid state drives).
** USB 3.1 Type C heads are intended to be a replacement for Micro-B 3.0 heads, and are not backwards compatible, but the Type C head was designed to support more wire contacts than currently in use in USB 3.1 and 4.0 standards in an effort to future-proof the standard for the next few years. There are also Type C to Type A plughead adaptors for certain devices that are strictly standards-compliant and thus properly backwards compatible to legacy USB hardware.
** As if data transfer protocols were a headache enough in the USB standard, it's made worse with ''power delivery'' compatibility as well. USB at the start only allowed for up to 0.5A at 5V of power delivery, as it was designed with basic peripherals in mind. Since then, ports may deliver up to 1A or 2A at 5V, with other standards like Anker's [=PowerIQ=], Qualcomm's Quick Charge, and USB-IF's USB PD. These standards provide a variety of current and voltages. Some devices cannot be powered or charged up, if it has a rechargable battery, with the base USB power delivery standard. While saner heads have made sure anything beyond 5V typically requires active handshaking, there are some passive handshaking methods (measuring resistors) that may suck up more current than the USB host can provide. Poorly designed electronics can actually fry USB hosts by taking more power than the host can handle. The existence of non-standard USB charging systems that allow more than 2A through the charging head makes it important to check the device's power requirements - For example, the Nintendo Switch uses a Type-C plug to deliver far more power than a typical phone charger can supply.
* 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.
** Sony's [=MemoryStick=] format in particular is one case since every consumer electronics device they manufactured in the 2000s (except for the UsefulNotes/PlayStation2) had a slot for it somewhere. (Evidently they hadn't learned their lesson from the Betamax.) That means your UsefulNotes/PlayStationPortable needs these special cards instead of just a normal SD card. Sony didn't wise up with the UsefulNotes/PlayStationVita either; though the [=MemoryStick=] format was gone by this point (indeed, Sony makes SD cards now), they still used a custom card format in an attempt to thwart pirates.
* 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 that 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.
* On the x86-64 architecture, 16-bit applications no longer work on 64-bit operating systems, which is now standard on any PC with 4GB or more of RAM. This is a combination of the OS no longer supporting the libraries and hooks needed to run 16-bit applications which nobody was using by the time 64-bit processors became mainstream and the processors themselves not supporting a specific 16-bit mode that nobody used in serious capacity by 2000. [[note]]x86-64 in 64-bit mode can run 16-bit applications if it can run in a protected memory environment. If it runs only on the so-called "Real Mode" which lacks memory protections, then the 64-bit mode won't run it.[[/note]] Curiously this is unique to the x86 family, as every other 64-bit architecture, if it wasn't a 64-bit architecture to begin with, evolved from a 32-bit only one.
* 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''. 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 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).
** A few years latter, Apple pulled the same move with UsefulNotes/MacOS, with [=macOS=] Catalina, launched in 2019, dropping support for 32-bit only applications.
* 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. This is going to get even worse in 2020, since the Python Foundation has announced that they will stop releasing updates for Python 2 at the start of that year, forcing developers to port all of their code to Python 3 or go without compatibility or security updates.
* 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.
* Between 1984 and 1986, Creator/TheBBC worked with some commercial partners and thousands of schoolchildren to create [[https://en.wikipedia.org/wiki/BBC_Domesday_Project "The Domesday Project"]], a vast multimedia picture of UsefulNotes/{{Britain}} at the time. The data was carefully stored... on UsefulNotes/LaserDisc, in a somewhat variant format. Since around 2002, when the problem became glaringly obvious, recovering and preserving all that data has since become a major project for a number of people.
* [=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.
* 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.
* 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=]. This trope will fully come into effect for Flash now that Adobe as well as the major browser developers have announced that they will discontinue Flash entirely in 2020.
** [=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.
* The latest kerfuffle in the PC world is the introduction of the Power Disable feature in SATA 3.3. The boneheaded feature required that pin 3 of the SATA power connector be held at 0 volts, or the drive will refuse to function. Many older power supplies deliver 3.3 volts to the pin, which happens to be the exact voltage to cause the drive to disable[[note]]There was short time where SATA [=SSDs=] actually only used the 3.3v rail to power themselves. Most [=SSDs=] nowadays run at 5v[[/note]]. And worse of all, they could’ve just installed a jumper on the drive to turn the feature off. Or as an alternative, choosing pin 4 instead, which is a ground pin, and making the drive reset if pin 4 does not make contact with pin 5 instead (which means the PSU could reset the drive just by breaking the connection between pin 4 and 5).
* The first edition of ''The Encyclopedia of Science Fiction'' was created in the late 1970s, and the text was carefully preserved on computer disks. When the time came to publish an updated second edition, about a decade later, it was discovered that not only were these 8" floppy disks, but they were in the format used by a defunct typesetting system -- something so obscure that the massed computer skills of SF fandom couldn't recover the contents. As this was before the onset of cheap, accurate text scanning, all 730,000 words of the first edition had to be retyped by hand.
* So far as a hardware specification goes, PCI-Express has averted this. PCI-Express slots and cards are both forwards and backwards compatible. The only penalty for installing a card that actually could use a later version PCI-Express slot is [[{{Nerf}} reduced performance]], such as the case of installing an AMD Radeon 5500XT in a [=PCIe=] 3.0 slot instead of a 4.0 slot it was designed for. There's no benefit however for installing a card meant for an earlier version in a later version slot as the slot will just configure itself for the earlier version. Whether or not the actual computer can use the hardware is another story though.
* Wireless communication protocols in general have come and gone over the years. Anything predating Wi-Fi is no longer in any real use. Earlier Wi-Fi standards like 802.11 a/b/g are pretty much unsupported these days in modern Wi-Fi networks. Heck, even earlier cellular network standards are starting to shut down. Have a 2G or 3G phone? Good luck connecting it to a network in places where 4G has reigned supreme. This is unlike say a wired communication protocol like Ethernet, which remains mostly forwards and backwards compatible. The only hiccup maybe needing the right connector, but you can go very far with an [=8P8C=] modular connector.
[[/folder]]

[[folder:Video Games]]
[[AC: General]]
* The major reason why backwards compatibility is hard to come by in most consoles is that the manufacturer often chooses to use completely different hardware 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 may 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. The costs to ensure that all titles work generally 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).
* Traditional light gun peripherals such as the [[UsefulNotes/NintendoEntertainmentSystem NES]] Zapper will not work on modern [=HDTVs=] since they rely on the specific way in which CRT [=TVs=] draw images in order to detect hits or misses.[[note]]It's actually far more complicated. It's discovered that firstly, there is a circuit on the zapper itself that filters out light from all but a very specific wavelength, which means the zapper has to be modified to remove this filter, or a third party gun that doesn't have the filter has to be used (easier than you think as most clone zapper guns don't have the filter, including the reproductions from Hyperkin). Secondly it was discovered that the programming of most games are ''very'' intolerant of lag, and even a 1ms lag is enough to trip up detection. When the game was patched to increase detection time, and used in conjunction with a gun that doesn't have the filter, the game worked. [[https://youtu.be/qCZ-Z-OZFUs This video]] explains things in more detail.[[/note]]
* While many [=HDTVs=] still let you hook up your old-school consoles with composite or S-Video, the result is far from ideal, as many a die-hard retro gamer will tell you, since most [=HDTVs=] aren't able to properly handle the types of signals that these consoles output.[[note]]Most consoles prior to the Dreamcast actually output a resolution of 240p or 288p, the latter of which was an unofficial mode best described as a hack within the standards of 480i and 576i. Most [=HDTVs=] can't properly handle these resolutions, which results an an overly interlaced and shifting image as well as extra input lag.[[/note]] While there are devices such as the [[https://solarisjapan.com/products/xrgb-mini-framemeister-compact-up-scaler-unit XRGB Mini Framemeister]] and the [[https://www.videogameperfection.com/products/open-source-converter/ Open Source Scan Converter]] that are designed to properly process the signals from classic consoles for display on a modern TV, [[CrackIsCheaper they don't come cheap.]] And if you thought that was bad, some television manufactures have taken the switch to 4K as an excuse to start phasing out these old-school analog inputs completely, meaning soon you'll have no way of using your retro consoles at all with your modern TV without one of the aforementioned expensive peripherals.

[[AC: Nintendo Consoles]]
* Until the hybrid console that is the UsefulNotes/NintendoSwitch entered the fray, each of Nintendo's portable consoles were backwards compatible with at least the previous generation system. Ergo:
** The UsefulNotes/GameBoyAdvance (barring the [=GameBoy=] Advance Micro) could play both UsefulNotes/GameBoy and UsefulNotes/GameBoyColor titles despite being a different architecture from the former [[note]]The Advance consoles use the [=ARM7TDMI=] architecture, a departure from the predecessors' use of the Z80 Architecture[[/note]]- Nintendo had included a z80 CPU on the handheld as a co-processor which does double duty as the main processor when working in Game Boy and Game Boy Color modes. [[note]]The [=GBC=] itself could play Game Boy titles, ''and vice versa'', because it was internally a revision of the Game Boy instead of a remodel.[[/note]] The Micro however lacked the backwards compatibility because it lacks the z80 co-processor found in previous Game Boy Advance systems- Nintendo had removed it to cut costs, reduce PCB size, and due to the fact that no [=GBA=] games actually use it.
** The different ISA of the UsefulNotes/NintendoDS meant that while the older GB and [=GBC=] titles couldn't work, [=GBA=] cartridges did work via a dedicated slot on the bottom of the original DS "Phat" and DS Lite models. This was possible because both the DS and GBA use the same [=ARM7TDMI=] architecture. The GBA slot was removed from the [=DSi=] even though the possibility to run GBA games was still there given that it was still the same CPU architecture- Nintendo probably removed the slot to combat piracy. [[note]]Nintendo probably removed the slot in a bid to combat flash carts (which at the time plugged into the GBA slot) as games that ran off the DS' slot are subject to a copy protection mechanism- which promptly fell flat on its face when the copy protection on the DS cart slot was cracked and flash carts that used the DS slot appeared as well.[[/note]]
** The UsefulNotes/Nintendo3DS doesn't have a slot of Game Boy Advance cartridges, but it can play all Nintendo DS cartridges, and thus all DS games that didn't require an extra accessory that required the GBA slot. Though the system would have to shut off parts of its OS to accomplish the task. Through the UsefulNotes/VirtualConsole, it could emulate GB and [=GBC=] titles, as well as [[UsefulNotes/NintendoEntertainmentSystem NES]] and [[UsefulNotes/SuperNintendoEntertainmentSystem SNES]] games.[[note]]Yes, it could also emulate [=GBA=] games- or rather, run them in a specific mode with parts of their OS shut off given the same architecture used, but this feature was limited to 20 games only made available for early adopters of the device.[[/note]]
* Early models of the UsefulNotes/{{Wii}} were not only capable of playing [[UsefulNotes/NintendoGameCube GameCube]] discs, but were even able to utilize some of the [=GameCube=]'s peripherals (like the microphone and the [=GBA=]-[=GameCube=] link cable). However, support for [=GameCube=] peripherals and games were dropped entirely from a new "Family Pack" model introduced in late-2011. And, of course, there's the Virtual Console.
* The UsefulNotes/WiiU retained backwards compatibility with UsefulNotes/{{Wii}} games and controllers, but lacks the ability to play [=GameCube=] discs natively.
* The UsefulNotes/NintendoSwitch is a cartridge-based system, thus it lacks the ability to play any [=Gamecube=]/Wii/Wii U games outside of emulation. Even getting past that, the system has a completely different hardware architecture than its 3 predecessors, using an ARM-based NVIDIA Tegra system-on-a-chip instead of the IBM [=PowerPC=] CPU/AMD GPU that the UsefulNotes/GameCube, UsefulNotes/{{Wii}}, and UsefulNotes/{{Wii U}} used. The different cartridge slot and form factor also divorces the system from the DS and [=3DS=] families as well.

[[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 [=PS3s=] were made with a different hardware set, and don't have any real emulation function at all.
** However, despite all the stuff involving the [=PS2=] library, all models of the UsefulNotes/PlayStation3 can still run [=PS1=] games just fine. Sony would also later introduce the "PS2 Classics" catalog where you could download emulated versions of [=PS2=] games regardless of whether your [=PS3=] had backwards compatibility or not.
* 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 older games to get around this]]. However, that still leaves you at the mercy of your Internet connection, and [[UsefulNotes/RegionCoding whether your region's GaiKai service has the games you want to play]]... [[NoExportForYou If it has the service at all]].

[[AC: Microsoft Consoles]]
* The UsefulNotes/Xbox360 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 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.]] Later, in 2017, Microsoft introduced backwards compatibility for original UsefulNotes/{{Xbox}} games, meaning that the Xbox One can now play games from the entire Xbox line of consoles.
* One of the first things announced for the Xbox One's successor, the Xbox Series X, was that it would be completely backwards compatible with the One; the Series X could run all One games, as well as all 360 and OG Xbox games that could run on it.

[[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. Creator/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''? Challenging another player online is no longer possible.
** ''VideoGame/PokemonBlackAndWhite'' and [[VideoGame/PokemonBlack2AndWhite2 their sequels]]? 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 phased out the Website/{{Miiverse}} services provided for the 3DS and Wii U in preparation to launch the more involved online services for the Switch. This means, for example, that the first ''VideoGame/{{Splatoon}}'''s grafitti system no longer works. ''VideoGame/Splatoon2'' took measures to prevent this from happening, with its graffiti system instead using Facebook or Twitter, neither of which will likely meet Miiverse's fate anytime soon.
* Gabe Newell of Creator/{{Valve|Software}} has sworn that if they ever shut down UsefulNotes/{{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 without modding the game.
** ''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/Fallout3'' 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=] UsefulNotes/{{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/SegaGenesis / Mega Drive with a second adapter (the Power Base Converter/Master System Convertor/Mega Adaptor) that duplicated some of the Master System's hardware (this was partly because the Genesis/Mega Drive 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 Sega (Mega) CD and UsefulNotes/SegaSaturn used the same storage medium, the CD[[note]]the cartridge slot on the Saturn is apparently a remnant from a phase of the project when both cartridges and CDs would've been used for games; the scrapped [[https://segaretro.org/Sega_Jupiter Sega Jupiter]] apparently would've been a Saturn without a CD drive, and could've been "upgraded" to a Saturn via a Sega CD-style add-on[[/note]] 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 (one developer for Creator/TravellersTales even noted that the GPU ISA is an evolved version of the Genesis GPU and is in fact backwards compatible) which 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 due to security concerns, 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 this 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.
* In a bit of irony, while games purchased from ''Website/GOGDotCom'' will work on older computers or [=OSes=], their installers won't. Attempting to launch the installer brings an error saying it's meant to run on a newer OS.
[[/folder]]

[[folder:Other]]
* [[UsefulNotes/{{VCR}} Betamax]]. U-Matic. Microcassette. Actually Magnetic Media as a whole- if you use any of these as part of your creative workflow, good luck- replacement hardware for these are now quite hard to come by, especially for those who're not part of the "Professional" bracket.
** 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]] 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.
* 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 some have a fairly extensive network that uses narrow gauge, which tends to be less of a problem because narrow-gauge rail is normally used for places too mountainous for anything wider[[/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.
* The good old 3.5mm stereo jack, one of the simplest and most widely-compatible connections that has been ubiquitous on practically every audio-producing or -receiving device for decades (and sometimes creatively used for purposes other than audio), appears to be on its way out. Smartphone makers, starting with Apple, have begun producing phones that lack this port, severely limiting their compatibility with your trusty old headphones, speakers, cars, and so forth.
[[/folder]]