iOS Hardware Guide

Hardware models

The following table summarizes iOS hardware available in devices of various generations:

Common to all iOS devices

• Screen: 320x480 pixels, LCD at 163ppi (unless stated otherwise)
• Built-in accelerometer
• Wi-Fi

Original iPhone

• ARM11, 412 Mhz CPU
• PowerVR MBX Lite 3D graphics processor
• 128MB of memory
• 2 megapixel camera
• Speaker and microphone
• Vibration support
• Silent switch

iPhone 3G

• ARM11, 412 Mhz CPU
• PowerVR MBX Lite 3D graphics processor
• 128MB of memory
• 2 megapixel camera
• Speaker and microphone
• Vibration support
• Silent switch
• GPS support

iPhone 3GS

• ARM Cortex A8, 600 MHz CPU
• PowerVR SGX graphics processor
• 256MB of memory
• 3 megapixel camera with video capture capability
• Speaker and microphone
• Vibration support
• Silent switch
• GPS support
• Compass support

iPhone 4

• ARM Cortex-A8 Apple A4 CPU
• ARM Cortex-A8 Apple A4 graphics processor
• 512MB of memory
• Cameras
  • Rear 5.0 MP backside illuminated CMOS image sensor with 720p HD video at 30 fps and LED flash
  • Front 0.3 MP (VGA) with geotagging, tap to focus, and 480p SD video at 30 fps
• Screen: 960x640 pixels, LCD at 326 ppi, 800:1 contrast ratio.
• Speaker and microphone
• Vibration Support
• Silent switch
• GPS support
• Compass Support

iPod Touch 1st generation

• ARM11, 412 Mhz CPU
• PowerVR MBX Lite 3D graphics processor
• 128MB of memory

iPod Touch 2nd generation

• ARM11, 533 Mhz CPU
• PowerVR MBX Lite 3D graphics processor
• 128MB of memory
• Speaker and microphone

iPad

• 1 GHz Apple A4 CPU
• Wifi + Blueooth + (3G Cellular HSDPA, 2G cellular EDGE on the 3G version)
• Accelerometer, ambient light sensor, magnetometer (for digital compass)
• Mechanical keys: Home, sleep, screen rotation lock, volume.
• Screen: 1024x768 pixels, LCD at 132 ppi, LED-backlit.

Graphics Processing Unit and Hidden Surface Removal

The iPhone/iPad graphics processing unit (GPU) is a Tile-Based Deferred Renderer. In contrast with most GPUs in desktop computers, the iPhone/iPad GPU focuses on minimizing the work required to render an image as early as possible in the processing of a scene. That way, only the visible pixels will consume processing resources.

The GPU's frame buffer is divided up into tiles and rendering happens tile by tile. First, triangles for the whole frame are gathered and assigned to the tiles. Then, visible fragments of each triangle are chosen. Finally, the selected triangle fragments are passed to the rasterizer (triangle fragments occluded from the camera are rejected at this stage).

In other words, the iPhone/iPad GPU implements a Hidden Surface Removal operation at reduced cost. Such an architecture consumes less memory bandwidth, has lower power consumption and utilizes the texture cache better. Tile-Based Deferred Rendering allows the device to reject occluded fragments before actual rasterization, which helps to keep overdraw low.

For more information see also:-

• POWERVR MBX Technology Overview
• Apple Notes on iPhone/iPad GPU and OpenGL ES
• Apple Performance Advices for OpenGL ES in General
• Apple Performance Advices for OpenGL ES Shaders

SGX series

Starting with the iPhone 3GS, newer devices are equipped with the SGX series of GPUs. The SGX series features support for the OpenGL ES2.0 rendering API and vertex and pixel shaders. The Fixed-function pipeline is not supported natively on such GPUs, but instead is emulated by generating vertex and pixel shaders with analogous functionality on the fly.

The SGX series fully supports MultiSample anti-aliasing.

MBX series

Older devices such as the original iPhone, iPhone 3G and iPod Touch 1st and 2nd Generation are equipped with the MBX series of GPUs. The MBX series supports only OpenGL ES1.1, the fixed function Transform/Lighting pipeline and two textures per fragment.

Texture Compression

The only texture compression format supported by iOS is PVRTC. PVRTC provides support for RGB and RGBA (color information plus an alpha channel) texture formats and can compress a single pixel to two or four bits.

The PVRTC format is essential to reduce the memory footprint and to reduce consumption of memory bandwidth (ie, the rate at which data can be read from memory, which is usually very limited on mobile devices).

Vertex Processing Unit

The iPhone/iPad has a dedicated unit responsible for vertex processing which runs calculations in parallel with rasterization. In order to achieve better parallelization, the iPhone/iPad processes vertices one frame ahead of the rasterizer.

Unified Memory Architecture

Both the CPU and GPU on the iPhone/iPad share the same memory. The advantage is that you don't need to worry about running out of video memory for your textures (unless, of course, you run out of main memory too). The disadvantage is that you share the same memory bandwidth for gameplay and graphics. The more memory bandwidth you dedicate to graphics, the less you will have for gameplay and physics.

Multimedia CoProcessing Unit

The iPhone/iPad main CPU is equipped with a powerful SIMD (Single Instruction, Multiple Data) coprocessor supporting either the VFP or the NEON architecture. The Unity iOS run-time takes advantage of these units for multiple tasks such as calculating skinned mesh transformations, geometry batching, audio processing and other calculation-intensive operations.

Page last updated: 2011-11-03