Why do video game cartridges and motherboards need a battery to maintain save data but a simple SD card does not?


Why do video game cartridges and motherboards need a battery to maintain save data but a simple SD card does not?

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Around the 80/90s era, reprogrammable flash memory was still very expensive, even in the small sizes needed for game saves.

It was often cheaper to include a small amount of battery powered RAM inside the game cartridge, but this also meant that the failure of that battery would result in the loss of the game save data.

Over time (especially around the game boy advance era), flash memory became cheap enough that it was practical to use in game cartridges).

Motherboards use the battery to keep an internal clock running when there is no power.

Old game cartridges used volatile memory. Like the RAM in the computer. It needed constant power to keep the data good. This was from before when the flash storage was easily available.

Old-school video game cartridges like those used on the Nintendo used NVRAM as a storage medium. NVRAM can hold a few bytes of information but has the downside that it needs a constant source of power (a battery) to hold it’s data. If the power source is lost, the files on the NVRAM are lost. The solution was to put a common watch battery inside the NES cartridge.

Around the same time EEPROM was invented. These are chips that included a technology called a floating gate, a trick of physics that allows a circuit to store electrons even when the power is disconnected. This allows the circuit to hold it’s data even when the power is disconnected. More importantly EEPROMs were re-programmable meaning you could erase them and upload new data.

EEPROMs were common place but expensive, and they were old school microchips meaning that the prongs or legs on the chip were very easy to snap off so they weren’t suitable for a child’s Video Game Console.

By comparison floppy diskettes were ubiquitous, cheaper, and more practical at the time. Which is why the Famicom (the Japanese NES) had a floppy drive accessory.

Modern SDcards are the evolution of this same technology. The same floating gate technology has been miniaturized and made significantly cheaper. They are also now in the form of a card (essentially a miniature cartridge) which makes them far more practical.

These are what are called Flash Storage, a reference both to the digital cameras they were originally designed for and the process of erasure which involves applying a current to the chips.

If they were to make NES cartridges today, they would use SD technology for saving data. In fact the 3DS cartridge is exactly that.

I’m assuming that you are talking about old video game like a game boy cartridge? Mother boards and those cartridges operate on volatile memory (ex. RAM) onboard and therefore require power to maintain the data.

For game cartridges this is because flash memory (non volatile) was prohibitively expensive when those games where being manufactured. For motherboards the volatile memory is only used to operate the cmos, bios, and clock information, the programming required to start your system.

As far as a motherboard goes I’ll explain it in mechanical terms. A car uses a battery to crank a starter and ignite a spark in the block. Once the car is running it uses the alternator to run the electronics leaving the battery to charge for the next start up.

The watch battery on your mobo allows the cpu systems to come online before the main data storage is online activating the programs and accessing memory required to make the computer work. (Not a perfect analogy as the PSU of your computer immediately turns on and powers up those systems.) but for visual aid I think it works.

these devices use volatile memory ot store their data

for cartridges this was a necessity of the time since nonvolatile memory was expensive and the majority of it was used to store the data of the game itself which you could set as Read only(ROM).

for motherboards its used to save the clock state and any options required(this is known as the CMOS) while the BIOS/UEFI exists in a type of memory meant to be read only except under a specific setup(EEPROM).