Hardware
Display
The display of the iPhone 4 is designed by Apple and is manufactured by LG. It features an LED backlit TFT LCD capacitive touchscreen with a pixel densityof 326 pixels per inch (ppi) on a 3.5 in (8.9 cm) (diagonally measured), 960×640 display. Each pixel is 78 micrometres in width. The display has a contrast ratio of 800:1. The screen is marketed by Apple as the "Retina Display", based on the assertion that a display of approximately 300 ppi at a distance of 12 inches (305 mm) from one's eye is the maximum amount of detail that the human retina can process.[35] With the iPhone expected to be used at a distance of about 12 inches from the eyes, a higher resolution would allegedly have no effect on the image's apparent quality as the maximum potential of the human eye has already been met.
This claim has been disputed. Raymond Soneira, president of DisplayMate Technologies, said in an interview with Wired Magazine, that the claims by Jobs are something of an exaggeration: "It is reasonably close to being a perfect display, but Steve pushed it a little too far." Soneira stated that the resolution of the human retina is higher than claimed by Apple, working out to 477 ppi at 12 inches (305 mm) from the eyes.[36]
However, Phil Plait, author of Bad Astronomy, whose career includes a collaboration with NASA regarding the camera on the Hubble Space Telescope, responded to the criticism by stating that "if you have [better than 20/20] eyesight, then at one foot away the iPhone 4’s pixels are resolved. The picture will look pixellated. If you have average eyesight, the picture will look just fine."[37][38]
Camera
The iPhone 4 features an additional front-facing VGA camera, and an improved (backslide-illuminated, big physical pixel size) 5 megapixel rear-facing camera integrated with an LED flash. The rear-facing camera is capable of recording HD video in 720p at 30 frames per second. Both cameras make use of the tap to focus feature, part of iOS 4, for photo and video recording.[39] The rear-facing camera has a 5× digital zoom.
Connectivity
In contrast to Steve Jobs' announcement at WWDC 2010, recent Federal Communications Commission documentation has shown that the iPhone 4 contains a Penta-Band 3G UMTS antenna, not a Quad-Band 3G UMTS radio, as advertised by Apple. According to the FCC documentation filed by Apple, the radio inside the iPhone 4 supports 800, 850, 900, 1900, and 2100 MHz. The 800 MHz frequency, which is most commonly used in Japanese mobile phones, is not advertised as being supported by Apple.[40] However, the 800 MHz band is a subset of the 850 MHz band, which probably explains why the device is advertised as Quad-Band[citation needed]. The chip-sets were manufactured by Skyworks Solutions[41] and Infineon for GSM version.
As with many other products manufactured by Apple, the iPhone 4 also uses the 30 pin dock connector as its only external data port.
Gyroscope and accelerometer
The iPhone 4 introduces a gyroscopic sensor that detects 3-axis angular acceleration around the X, Y and Z axes, enabling precise calculation of yaw, pitch, and roll. The gyroscope complements the accelerometer, a sensor that has been present since the original iPhone, which detects the device's acceleration, shake, vibration shock, or fall by detecting linear acceleration along one of three axes (X, Y and Z). The combined data from the accelerometer and the gyroscope provides detailed and precise information about the device's 6-axis movement in space. The 3 axes of the gyroscope combined with the 3 axes of the accelerometer enable the device to recognize approximately how far, fast, and in which direction it has moved in space.[42]
Processor and memory
The iPhone 4 is powered by the Apple A4 chip, which was designed by Intrinsity[citation needed] and, like all previous iPhone models, manufactured by Samsung.[43] This system-on-a-chip is composed of a Cortex-A8 CPU integrated with a PowerVR SGX 535 GPU.[44] The Apple A4 is also used in the iPad where it is clocked at its rated speed of 1 GHz. The clock speed in the iPhone 4 has not been disclosed . All previous models of the iPhone have underclocked the CPU, which typically extends battery life and lowers heat dissipation.
The iPhone 4 has 512 MB of eDRAM. The additional eDRAM supports increased performance and multi-tasking.[45]
Storage and Micro-SIM
The iPhone 4 uses a Micro-SIM card on iPhone 4 devices running on a GSM network, which is positioned in an ejectable tray, located on the right side of the device. On a CDMA network, however, the phone connects to the network using an ESN. All previous models have used regular Mini-SIM cards. Depending on the operator, Micro-SIM cards may not be available for all networks globally. As a technical workaround it is possible to trim a Mini-SIM card with a knife or scissors so that it fits into the Micro-SIM tray.
As on previous models, all data is stored in flash memory, 16GB or 32GB, and not on the SIM. Unlike previous generations, the storage capacity is not printed on the back of the unit.