User Data Storage Peripheral - Dismantled for reference and curiosity
Directly above the Sony Playstation's controller ports are two slots where gamers can insert a Sony PlayStation Memory Card.
Memory cards were a huge boon to gamers sick to death of having to write down level codes as part of the reward for completing an arduous boss battle. While the feature had been available on select other consoles it hadn't been as widely promoted or distributed.
The first run of PlayStation Memory Cards were one megabyte and that equated to fifteen save game blocks of data. Later releases offered up to four megabytes of storage space.
While users can save progress mid-game in titles that supported the feature, you can't manage the data in-game or completely delete data. Starting the PlayStation without a CD in the drive or with the CD door open boots the PlayStation into its OS that incorporates a Memory Card manager for this purpose.
Genuine Sony Memory Cards (and many aftermarket offerings) shipped with an adhesive label for gamers to record what was on the card or which of two warring siblings it belonged to.
While some earlier console ROM cartridge titles included an internal battery to save progress, it wasn't until memory cards came on the scene that this feature really developed allowing for complex RPG and like titles to flourish.