Comparison among iPods

Model	1st generation	2nd generation	3rd generation	4th generation
Status	Discontinued	Discontinued	Discontinued	In Production
Initial operating system	iPhone OS 1.1	iPhone OS 2.1.1 iPhone OS 3.1.1 (8 GB MC model)	iPhone OS 3.1.1	iOS 4.1
Highest Supported operating system	iPhone OS 3.1.3	iOS 4.2.1	iOS 4.3.4 iOS 5.0 (Beta versions)
Display	3.5 in (89 mm), 3:2 aspect ratio, glossy glass covered screen, 262,144-color LCD, 480×320 px (HVGA) at 163 ppi			3.5 in (89 mm), 3:2 aspect ratio, 24-bit color, glossy glass-covered LED-backlit LCD, 960×640 px at 326 ppi
Storage	8, 16 and 32 GB		32 and 64 GB	8, 32 and 64 GB
CPU Core / Processor	620 MHz (underclocked to 412 MHz, originally 400 MHz) Samsung 32-bit RISC ARM 1176JZ(F)-S v1.0	620 MHz (underclocked to 533 MHz) Samsung ARM11 core with internal ARM7 core for Jazelle acceleration	833 MHz (underclocked to 600 MHz) ARM Cortex-A8	1 GHz (underclocked to 800 MHz) ARM Cortex-A8 Apple A4
Graphics	PowerVR MBX Lite 3D GPU		PowerVR SGX535 GPU
Memory	128 MB DRAM		256 MB DRAM
Connectivity	Wi-Fi (802.11b/g), USB 2.0/Dock connector	In addition to previous: Bluetooth 2.1 + EDR (requires iPhone OS 3.0), Built-in speaker, Hardware volume controls, Nike+	In addition to previous: Voice Control, Includes earphones with remote and mic	In addition to previous: 802.11n (2.4 GHz only) 3-axis gyroscope Built-in microphone
GPS	N/A
Digital compass	N/A
Camera	N/A			Rear 0.7 MP backside illuminated CMOS image sensor with video (720p HD at 30 frame/s), Front VGA-quality photos and video at up to 30 frame/s.
Audio codec	Wolfson Microelectronics WM8758BG	Cirrus Logic CS4398	Cirrus Logic CS4398	Cirrus Logic (similar to iPhone 4)
Materials	Stainless steel back and aluminum bezel; plastic for Wi-Fi antenna	Contoured stainless steel back and bezel; plastic for Wi-Fi and Bluetooth antenna		no plastic for antenna
Power	Built-in rechargeable lithium-ion polymer battery
	3.7 V 2.15 W·h (580 mA·h)	3.7 V 2.73 W·h (739 mA·h)	3.7 V 2.92 W·h (789 mA·h)	3.7 V 3.44 W·h (930 mA·h)
Rated Battery life (hours)	audio: 22 video: 5	audio: 22 video: 5	audio: 30 video: 6	audio: 40 video: 7
Dimensions	110×61.8×8 mm (4.3×2.4×0.31 in)	110×61.8×8.5 mm (4.3×2.4×0.33 in)		110×58×7.1 mm (4.4×2.3×0.28 in)
Weight	120 g (4.2 oz)	115 g (4.05 oz)		101 g (3.6 oz)
Released	8 and 16 GB: September 14, 2007 32 GB: February 5, 2008	9-Sep-08	9-Sep-09	8-Sep-10
Discontinued	9-Sep-08	16 and 32 GB: September 9, 2009 8 GB: September 1, 2010	1-Sep-10	In production