Hardware

Chipsets and electronics
Microcontroller
iPod first to third generations — Two ARM 7TDMI-derived CPUs running at 90 MHz.
iPod 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-Chip, based around an ARM processor.[12]
iPod shuffle first generation — SigmaTel STMP3550 chip that handles both the music decoding and the audio circuitry.[13]
Audio chip
All iPods (except the shuffle and 6G) use audio codecs developed by Wolfson Microelectronics.
Sixth generation iPods use a Cirrus Logic audio codec chip.
Storage medium
iPod first to fifth generation — 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) Microdrives manufactured by Hitachi and Seagate
iPod nano — Flash memory from Samsung, Toshiba, and others.
iPod shuffle — Flash memory
Batteries
iPod first and second generation, nano, shuffle — Internal lithium polymer batteries
iPod third to fifth generation — Internal lithium-ion batteries