Atmel AT89C51SND1 - Manual (Page 6)

Overview
AT89C51SND1 Reference Design User Guide 2-4
4207B–MP3–04/07
Figure 2-2. Reference Design (bottom view)
The battery is a standard 1.5V-battery type AAA.
The mass storage system on the board is a 64 MB NAND Flash memory.
2.1 User Interface The user interface has 4 LEDs and 5 push-buttons:
Play/Pause
Function
Previous - Minus
Next - Plus
ON (Pwr)