question: Why could retro cartridge-based games not save player data without a battery backup? Why do modern cartridge-based systems not let you do this as well?
comment: Technology like the Non-volatile memory in SDcards didn't exist yet, or at least not in a commercially viable form. If the classic NES was made today the system would contain either a hard drive, an SDcard slot, or a portion of non-volatile memory on the motherboard. The Cartridges used on older systems like an Atari or Nintendo were ROMs. Read-Only-Memory The chips were created at the factory without the ability to be modified so there was no way to store dynamic information on them. To get around this cartridges would have a small amount of NVRAM (Non-Volatile Random Access Memory) that could store variables (like what level you are on, your life total, which weapons you unlocked, etc) even if the power was shut down. NVRAM can only keep its contents if it has a constantly power source, which in the case of Nintendo games was a small watch battery inside the cartridge. > Furthermore with the advancements in storage and us now having SD cards the size of ones fingernail why cant player data be stored on a a Nintendo 3DS/Switch cart? They total could, they just don't :D There is no reason that Nintendo couldn't use common SDCard technology to release video games for a portable system, other than they don't want to. Probably for anti-piracy reasons.
passages: Cartridge-based video games sometimes contain a battery which is used to preserve the contents of a small RAM chip on which saved games and/or high scores are recorded.
  
  Section::::Examples.:Hospitals.
  
  Power failure in a hospital would result in life-threatening conditions for patients. Patients undergoing surgery or on life support are reliant on a consistent power supply. Backup generators or batteries supply power to critical equipment until main power can be restored.
  
  Section::::Examples.:Power Stations.
   Section::::Backup devices for handhelds.
  
  Section::::Backup devices for handhelds.:Game Boy.
  
  For the original Game Boy and its color successor there are numerous external copiers, such as GB Xchanger, which can back up an inserted Game Boy or Game Boy Color cartridge. The GB Xchanger plugs into a computer in order to copy the games, which can later transfer the game(s) back through the copier to a blank flash cartridge.
  
  Section::::Backup devices for handhelds.:Game Boy Advance.
   Section::::Backup devices for consoles.:Nintendo 64.
   With the advent of optical based media at the tail end of the 16-bit era, data could not be stored on the game media, and a saved game required the introduction of non-volatile memory to the console either in the form of internal memory or memory cards (both of which were introduced with the Sega CD) which stored game data once the system was powered off; passwords avoided the need for this.
   In the fifth generation of video game consoles, passwords retained practical use in conserving memory blocks. Platform and puzzle games often required no data to be preserved other than the level achieved – which was easily encoded in a simple password – and thus using one of the limited blocks for this data was seen as wasteful. More importantly, some consoles of the time, such as the PlayStation and Jaguar CD, had no memory available for saves out of the box, and the need to purchase separately sold memory cards could be a deterrent to purchasing a game.
   Some models of Palm keep their data storage in volatile memory and require constant power to maintain their memory. Although these handhelds attempt to save the contents of memory in low battery situations by not "turning on," leaving a "dead" handheld for an extended period of time can cause this reserve power to be used up and the contents of storage memory to be lost. Some later Palms use NVRAM or microdrive for storage.
   Section::::Rationale and history.
  
  Passwords were used when storage was either impossible or expensive. On early ROM cartridges, games could not be saved without an additional memory card being integrated into the game, significantly increasing (often doubling) the manufacturing cost. By using passwords, nothing needed to be written on the cartridge, as the password itself contained all the information needed to continue the game, and thus a memory card was not necessary, lowering costs. These costs were particularly a concern on low volume titles by smaller third-party developers.
   Each video game is stored on a plastic cartridge, officially called a "Software Cartridge" by SNK. The cartridge provides the code and game data to the console's CPU. Some cartridges include a small battery with SRAM, flash memory chip, or EEPROM, which allows game data to be saved when the console is turned off. If the battery runs out in a cartridge, then the save data will be lost, however, it is possible to replace the battery with a new battery. To do this, the cartridge must be unscrewed, opened up, and the old battery would be removed and replaced. This may require desoldering the dead battery and soldering the replacement in place. SNK used round, flat watch batteries for saving information on the cartridges.
   Unlike other Palm computers, which had rechargeable batteries, they were designed to run on standard dry cell batteries (except for the m130, which uses a rechargeable battery). Data preservation occurred via a backup battery system that had a very short life and high voltage volatility, such that users had to change dry-cell batteries one at a time; users who removed all the batteries and then replaced them all could find that the backup battery had died in the time that it took to change the batteries, resulting in loss of unit memory.
   The relative complexity and inconvenience of storing game state information on early home computers (and the fact that early video game consoles had no non-volatile data storage) meant that initially game saves were represented as "passwords" (often strings of characters that encoded the game state) that players could write down and later input into the game when resuming.
   For both of these devices, the dynamic RAM requires continuous power to retain data; when power is lost, the data fades away. For the Rocket Drive, there was a connector for an external power supply separate from the computer, and the option for an external battery to retain data during a power failure. The i-RAM included a small battery directly on the expansion board, for 10-16 hours of protection.
   Section::::Backup devices for consoles.:Super Nintendo Entertainment System.
  
  16 bit game backup devices using floppy disks or USB.
  
  BULLET::::- Super Magicom (8 or 16 Megabits) - by Front Fareast Industrial, model MS-3201. Included an external 3.5" floppy drive and integrated parallel port. File format is *.SMC; for multi-disk images, *.SMC followed by *.001, *.002, ...
   BULLET::::- Retrode by Retrode UG is a USB interface for both Sega Genesis and SNES cartridges and controllers. It can be extended via so-called plug-in adapters to accommodate games for other systems as well.
   The cartridges are also prone to breaking. The LCD can easily rot and the connections can break, improperly covering up the sprites during game-play, hindering the visuals of the game partially or completely. In other cases the game just stops working at all.
   Modern day devices include the Everdrive 64 and the 64drive. The Everdrive loads ROM images from either USB or from SD card inserted into the top of the cartridge. The 64Drive also uses USB but can also load games from either SD card or compact Flash card. Both units require a CIC chip soldering into the board and the plastic casing from a donor cartridge. Neither unit has the ability to backup cartridges. You can however backup cartridges using a device called Retrode, this is USB powered device that installs itself as a mass storage device in windows, allowing the cartridge information to be backed up.
   Early cartridges had storage limitations which grew in size as the technology developed. They provided more security against third party developers and the illegal copying of games. Some could be partially re-writable allowing for games to save their data to the cartridge itself meaning no extra saving media was required.
  
  While cartridges became less popular with the introduction of disc based media, they are still popular to use for handheld consoles and are still in use on consoles in later generations such as the Nintendo Switch.
  
  Section::::Technology.:Storage.:Disc.
   On later cartridge-based console games, such as "Kirby's Adventure" and "The Legend of Zelda", saved games were stored in battery-backed RAM on the game cartridge itself. In recent consoles, which use disc-based media for storing games, saved games are stored in other ways, such as by use of memory cards or internal hard drives on the game machine itself.
  
  Some games do not save the player's progress towards completing the game, but rather high scores, custom settings, and other features. The first game to save the player's score was Taito's seminal 1978 shoot 'em up title "Space Invaders".
   BULLET::::- Game Doctor Series - by Bung Enterprise. Available up to 64 Megabits (and upgradable to 128 Megabits) with optional Digital Signal Processor cartridge to run games like Pilot Wings, Super Mario Kart and many others. File format extension is *.078.
  
  BULLET::::- Multi Game Hunter (MGH) by Venus Corp. A dual solution game copier for both Sega Genesis and SNES.
  
  BULLET::::- Double Pro Fighter by China Coach Limited is a dual solution game copier for both Sega Genesis and SNES.
   It is important to note that no commercially produced Backup Device for Super Nintendo can play back games which use additional processing hardware in the cartridge, with the sole exception of DSP-1. This is due in part to the way in which these processors operate. It may be possible with some copiers to manage to back up a game using an extra coprocessor chip though. A relatively small number of games fall into this category, but there are notable games included, for example "Mega Man X2", "Mega Man X3", "Star Fox", "Kirby's Dream Land 3", "Super Mario RPG", and "".
   Passwords are a form of saved game not stored on non-volatile memory. Instead, everything needed to reconstruct the game state is encoded in a string of text (the password) and displayed to the player, who can then record or memorize it. The player may later resume play from that point by entering the same password. Passwords are only feasible when the amount of data being saved is only a few bytes.
  
  Section::::Types of saved games.:Save states.
   Drawbacks to the Adventure Vision are its monochrome (red) screen as well as the mirror motor, which draws a great deal of power from the batteries. The latter problem can be avoided by the use of the built-in AC adapter port.
  
  Entex released four games for the Adventure Vision:
  
  BULLET::::- "Defender", based on the Williams Electronics arcade game of the same name
  
  BULLET::::- "Super Cobra", based on the Konami arcade game of the same name
  
  BULLET::::- "Turtles", based on the Konami arcade game of the same name (similar to "Pac-Man")
   A game backup device, formerly usually called a copier and more recently a flash cartridge, is a device for backing up ROM information from a video game cartridge to a computer file called a ROM image and playing them back on the real hardware. Recently flash cartridges, especially on the Game Boy Advance and Nintendo DS platforms, only support the latter function; they cannot be used for backing up ROM data. Game backup devices also make it possible to develop homebrew software on video game systems. Game backup devices differ from modchips in that modchips are used in conjunction with systems that use generally available media such as CDs and DVDs, whereas game backup devices are used with systems that use cartridges.
   Modern personal computer motherboards have a backup battery to run the real-time clock circuit and retain configuration memory while the system is turned off. This is often called the CMOS battery or BIOS battery. The original IBM AT through to the PS/2 range, used a relatively large primary lithium battery, compared to later models, to retain the clock and configuration memory. These early machines required the backup battery to be replaced periodically due to the relatively large power consumption. Some manufacturers of clone machines used a rechargeable battery to avoid the problems that could be created by a failing battery. Modern systems use a coin style primary battery. In these later machines, the current draw is almost negligible and the primary batteries usually outlast the system that they support. It is rare to find rechargeable batteries in such systems.
   Even though third-party rechargeable batteries were available for the battery-hungry alternatives to the Game Boy, these batteries employed a nickel-cadmium process and had to be completely discharged before being recharged to ensure maximum efficiency; lead-acid batteries could be used with automobile circuit limiters (cigarette lighter plug devices); but the batteries had mediocre portability. The later NiMH batteries, which do not share this requirement for maximum efficiency, were not released until the late 1990s, years after the Game Gear, Atari Lynx, and original Game Boy had been discontinued. During the time when technologically superior handhelds had strict technical limitations, batteries had a very low mAh rating since batteries with heavy power density were not yet available.
   The NES version of "Rygar" did not allow for game saves. The complexity and difficulty of the game, along with the puzzles to solve and special objects needed to progress, require a great deal of time and unlike other complex adventure games of the time, the cartridge did not contain a battery, nor did it contain a password feature. As a result, many players were forced to pause the game and leave their NES on overnight (to resume the next day), sometimes going on for days or even weeks, before finally obtaining the necessary items and power to finish the game. If the unit was accidentally turned off, unplugged, or if it malfunctioned, all game data would be lost and the player would be forced to start over from the beginning.
  