The coolest thing for programming is Rockbox , an open-source project, that allows the programmer to have a go at optional features. The Rockbox port for the Sansa Fuze has been quite successful.
Rockbox is a separate firmware that resides alongside, but doesn’t completely replace, the original firmware. The Fuze can be set up as a dual-boot device.
Check out Rockbox.org for details; the fuze is a stable port currently. For the programmer, the user guide is at least 150 pages if I recall. There is a text reader function too, as well as plenty of customizable functions. The Fuze’s screen is small, so choosing a decent font is important. Using a green monochrome on black is sharp, reminds me of using CP/M and the Z-80.
Bob :smileyvery-happy: