Backward compatibility
Backward compatibility is the ability for a newer technology to work with older technology and typically applies to electronic hardware, operating systems, and software. For example, if a person buys a new model of computer, and the spreadsheet program from their older model computer still works on the new model, then the new model is backward compatible with the old model. However, if the new model of computer cannot run the old spreadsheet program, then the new model is said to have broken backward compatibility.
Backward compatibility is beneficial to users of a technology because they don't have to repurchase any related products, making it a big selling point for the manufacturer. When DVD discs replaced VHS tapes, and people replaced their VHS players with DVD players, they could no longer watch their old VHS tapes, so they had to buy their movies all over again on DVD. However, most Blu-ray players were backward compatible with DVDs, so, when people switched to the newer technology, they did not have to buy their movies again. If a customer knows all their existing products will still work, they're more likely to replace their old technology with a newer one.
However, backward compatibility is a problem for technology manufacturers. Supporting older technology often means adding a lot of expensive components that would otherwise be unnecessary. For example, when Sega designed the Genesis, they wanted it to be backward compatible with the Master System, but the Genesis's audio chip was incompatible with the one in the Master System. Because of this, the Genesis needed to include an otherwise unnecessary chip which not only increased the complexity of the Genesis's design, but also its cost. Since designing a product as cheaply as possible to reach a certain specification is the goal of hardware manufacturers, and backward compatibility almost always increases a product's final cost, it is frequently left out of the new design.
Backward compatibility can also require newer hardware to be tied to obsolete components. Atari wanted their Atari 7800 to be backward compatible with the Atari 2600 which meant including the 2600's TIA chip. By the early 1980s, the TIA was quite obsolete, but it could generate sound, and adding a whole new audio chip would make the 7800 cost even more. The decision was made to only use the TIA chip for audio, resulting in the 7800 sounding inferior to all other consoles of the time. An even worse example can be seen with Nintendo when they started designing the Super Famicom. They initially decided on a rather obscure and slow chip for their CPU because it would allow backward compatibility with the Famicom. However, as they began designing the rest of the console's components, it became clear that it was impossible to maintain compatibility and still have a decent console. They broke backward compatibility, but were then too far along in the console's design to switch the CPU for something more powerful. This resulted in the Super Famicom, and likewise the Super Nintendo Entertainment System, having an under-powered CPU with nothing to show for it.
Backward compatibility has similarities to forward compatibility, extensibility, and cross-platform compatibility.
Contents
Examples
As computers overtake older generations, they become powerful enough to emulate earlier models entirely through software, which is similar to software backward compatibility. However, this section only lists devices which offer native backward compatibility without emulation.
Home Media
- Most Blu-ray and HD-DVD players can also play DVDs.
- Most Ultra HD Blu-ray players can also play Blu-ray and DVDs.
Home Computers
| Computer Model | Released | Backward Compatible With | Software | Hardware | Notes |
|---|---|---|---|---|---|
| Apple IIgs | 1986-09-15 | Apple II | Most software | ? | Included the bulk of an Apple II on a single board. |
| Aptiva | 1994-09-?? | IBM PS/1 | Most software | Most hardware | |
| Commodore 64 | 1982-08-?? | Commodore VIC-20 | None | Most hardware peripherals | |
| Commodore 128 | 1985-01-?? | Commodore 64 | All software | Most hardware peripherals | Could run in backward compatibility mode. |
| Commodore VIC-20 | 1980-??-?? | Commodore PET | None | Most hardware peripherals | |
| IBM PCjr | 1984-03-?? | IBM PC | Some software | ? | |
| IBM PS/1 | 1990-??-?? | IBM PS/2 | Most software | Most hardware peripherals | |
| IBM PS/2 | 1987-04-?? | IBM PC | Most software | Most hardware peripherals | |
| Macintosh Classic | 1991-03-?? | Apple II | Most software | ? | Apple sold an Apple IIe Card but it only worked on early models. |
| MSX2 | 1985-??-?? | MSX | All software | Most hardware | |
| MSX2+ | 1988-??-?? | MSX, MSX2 | All software | Most hardware | |
| MSX TurboR | 1990-11-?? | MSX, MSX2, MSX2+ | All software | Most hardware | |
| TRS-80 Model III | 1980-07-?? | TRS-80 Model I | Some software | ? | A lot of software had to be patched by the manufacturer to work. |
Video Game Consoles
| Console | Released | Backward Compatible With | Notes |
|---|---|---|---|
| Atari 5200 | 1982-11-?? | Atari 2600 | Requires VCS Cartridge Adapter. Works on all 2 controller port models and select 4 controller port models. |
| Atari 7800 | 1986-05-?? | Atari 2600 | All games work. 2600 controllers work too, but only with the games that use one button. |
| Atari XEGS | 1987-??-?? | Atari 8-bit | Cartridge games only. |
| Game Boy Color | 1998-10-21 | Game Boy | |
| Game Boy Advance | 2001-03-21 | Game Boy, Game Boy Color | Original and SP models, but not Micro. |
| Genesis | 1989-08-14 | Master System | Requires Power Base Converter. |
| Leapster Explorer | 2010-06-?? | Leapster2 | |
| Master System | 1986-09-?? | Sega SG-1000 | |
| Neo Geo Pocket Color | 1999-03-16 | Neo Geo Pocket | |
| Nintendo DS | 2004-11-21 | Game Boy Advance | Original and Lite models. |
| Nintendo DSi | 2008-11-01 | Nintendo DS | |
| Nintendo 3DS | 2011-02-26 | Nintendo DS, Nintendo DSi | |
| New Nintendo 3DS | 2014-10-11 | Nintendo DS, Nintendo DSi, Nintendo 3DS | |
| PlayStation 2 | 2000-03-04 | PlayStation | Original model plays most games. Later models play fewer. |
| PlayStation 3 | 2006-11-11 | PlayStation, PlayStation 2 | Original model plays most games. Later models play fewer. |
| PlayStation 5 | 2020-11-12 | PlayStation 4, PlayStation VR | |
| Sega Mark III | 1985-10-20 | Sega SG-1000 | |
| Wii | 2006-11-19 | GameCube | Only first model Wii. |
| Wii U | 2012-11-18 | Wii | |
| Xbox 360 | 2005-11-22 | Xbox | Requires updates. 462 of 996 games. |
| Xbox One | 2013-11-22 | Xbox | 51 of 996 games |
| Xbox Series X/S | 2020-11-10 | Xbox, Xbox 360, Xbox One | All Xbox One, some Xbox 360, few Xbox. |
Software
In the early days of home computers, each new model had an entirely new set of hardware, firmware, and operating system making the software completely incompatible with the previous model. For example, none of the software developed for the Commodore PET will work on the Commodore VIC-20 and none of the VIC-20 software will work on the Commodore 64.
Most modern operating systems are backward compatible with the software designed for earlier releases, at least for several years. For example, a large portion of the software designed for Windows 3 runs on Windows 95, a lot of software developed for Windows 95 runs on Windows XP, and so forth all the way up to Windows 11. There is even some software originally designed for Windows 95 which runs flawlessly on Windows 11 despite a time gap of over 25 years.
Microchips
Microchips are often updated throughout the course of their lifespan with minor updates or revisions and are designed with backward compatibility in mind because it's very costly to redesign the circuit boards which utilize them. Because of this, chip manufacturers often make their updated chips "drop in" replacements where an older chip can be replaced with a new chip without any modifications to the board.
Most of Intel's x86 CPU line has been backward compatible with the instructions of previous chips. The Intel 80486 is backward compatible with the Intel 80386, which is backward compatible with the Intel 80286, which is backward compatible with the Intel 8086.
Links
- en.wikipedia.org/wiki/Category:Backward-compatible_video_game_consoles - Wikipedia - Backward compatible consoles.
- huguesjohnson.com/features/backwards - Gaming info.
