Hardware...wikipedia

Chipsets and Electronics

Chipset or Electronic	Product(s)	Component(s)
Microcontroller	iPod Classic first to third generations	Two ARM 7TDMI-derived CPUs running at 90 MHz
	iPod Classic fourth and fifth generations, iPod Mini, iPod Nano first generation	Variable-speed ARM 7TDMI CPUs, running at a peak of 80 MHz to save battery life
	iPod Nano second generation	Samsung System-on-a-chip, based around an ARM processor.[21][22]
	iPod Shuffle first generation	SigmaTel STMP3550 chip that handles both the music decoding and the audio circuitry.[23]
Audio Chip	All iPods (except the iPod Shuffle, 6G Classic and 2G Touch) [24]	Audio Codecs developed by Wolfson Microelectronics
	Sixth generation iPod Classic	Cirrus Logic Audio Codec Chip
Storage Medium	iPod Classic	45.7 mm (1.8 in) hard drives (ATA-6, 4200 rpm with proprietary connectors) made by Toshiba
	iPod Mini	25.4 mm (1 in) Microdrive by Hitachi and Seagate
	iPod Nano	Flash Memory from Samsung, Toshiba, and others
	iPod shuffle and Touch	Flash Memory
Batteries	iPod Classic first and second generation, Shuffle	Internal Lithium Polymer Batteries
	iPod Classic 3G onward, iPod Mini, iPod Nano, iPod Touch,	Internal Lithium-Ion Batteries
Display	iPod nano	2.2-inch (diagonal) color LCD with blue-white LED backlight, 320x240 resolution at 204 pixels per inch[25]
	iPod classic	2.5-inch (diagonal) color LCD with LED backlight, 320x240 resolution at 163 pixels per inch[26]
	iPod touch	3.5-inch (diagonal) widescreen Multi-Touch, 480x320 resolution at 163 pixels per inch[27]