In 2003, the menu and playlist functions were expanded. As hardware became smaller, the importance of software functionality increased.
NW-MS70D
The NW-MS70D is a Memory Stick Walkman equipped with built-in flash memory. It has 256MB of internal storage and supports expansion with Memory Stick Duo. It supports audio playback in ATRAC, ATRAC3, and ATRAC3plus formats and has a backlit LCD display.
NW-MS90D
The NW-MS90D was a third-generation Memory Stick Walkman that combined built-in flash memory with Memory Stick Duo expansion. It offered 512 MB of internal storage and supported ATRAC, ATRAC3, and ATRAC3plus playback through a backlit LCD. Gapless playback, Virtual Mobile Engine, and canal-type headphones were included, and the model built directly on the NW-MS70D's integrated-flash approach. The higher capacity made Sony's hybrid Memory Stick idea feel more complete. Earlier Memory Stick Walkmans treated the removable card as the center of the product. The NW-MS90D paired internal flash with Duo expansion, so it behaved more like a self-contained player that happened to allow extra storage. Gapless playback, stronger battery life, and a more mature compact design gave it a cleaner purpose than the earliest Memory Stick models. It was the high point of that branch before Sony's digital Walkman line settled more firmly around integrated flash players.
In 2003, the operating system for digital music playback was established. This means the structure has moved to the practical application stage.
