iPhones use flash memory, specifically NAND flash memory, as their internal storage device. NAND flash memory is a type of non-volatile storage technology that does not require power to retain data. It provides fast read and write speeds, making it well-suited for use in smartphones and other mobile devices.
What is NAND flash memory?
NAND flash memory is a type of flash memory developed by Toshiba in the late 1980s. The name NAND refers to the logic gate design used in its internal architecture. NAND flash memory stores data in an array of memory cells made up of floating-gate transistors. Unlike volatile forms of memory like DRAM and SRAM which lose data when power is removed, NAND flash retains data even when powered off. This makes it non-volatile.
Compared to other non-volatile memories like hard disk drives and optical discs, NAND flash provides much faster read and write performance, better physical durability, and reduced power consumption. These advantages make NAND flash memory the dominant choice for storage in consumer electronics like smartphones, tablets, and solid state drives (SSDs).
The iPhone uses a specific type of NAND flash memory called eMMC (embedded Multi-Media Controller). eMMC integrates the flash memory and a controller chip in the same BGA (ball grid array) package. This provides faster communication between the flash memory and controller, enabling better performance compared to discrete flash memory chips.
Benefits of NAND flash storage
There are several key benefits NAND flash storage provides for the iPhone:
- Faster read/write speeds – NAND flash memory can read and write data much faster than traditional hard disk drives. This enables fast launching of apps, quick saving of photos, and smooth 4K video recording.
- Durability – With no moving parts, NAND flash storage is more physically durable and reliable than hard disk drives.
- Lower power consumption – NAND flash memory consumes much less power than HDDs. This extends battery life on the iPhone.
- Smaller size – The compact design of NAND flash enables thinner and lighter iPhones.
- Silent operation – Absence of moving parts means NAND flash storage is completely silent.
For a mobile device like the iPhone where responsiveness, reliability, size, and battery life are critical, NAND flash memory provides major advantages over traditional storage technologies.
NAND flash storage capacity in iPhones
The storage capacity of NAND flash memory in iPhones has steadily increased over the years as technology has improved. Here is a look at the evolution of iPhone storage capacities:
| iPhone Model | Release Year | Base Storage Capacity |
|---|---|---|
| iPhone | 2007 | 4GB |
| iPhone 3G | 2008 | 8GB |
| iPhone 3GS | 2009 | 16GB |
| iPhone 4 | 2010 | 16GB |
| iPhone 4S | 2011 | 16GB |
| iPhone 5 | 2012 | 16GB |
| iPhone 5S | 2013 | 16GB |
| iPhone 6/6 Plus | 2014 | 16GB |
| iPhone 6S/6S Plus | 2015 | 16GB |
| iPhone SE | 2016 | 16GB |
| iPhone 7/7 Plus | 2016 | 32GB |
| iPhone 8/8 Plus | 2017 | 64GB |
| iPhone X | 2017 | 64GB |
| iPhone XR | 2018 | 64GB |
| iPhone XS/XS Max | 2018 | 64GB |
| iPhone 11/11 Pro | 2019 | 64GB |
| iPhone SE (2nd gen) | 2020 | 64GB |
| iPhone 12 mini/12 | 2020 | 64GB |
| iPhone 13 mini/13 | 2021 | 128GB |
| iPhone 14/14 Plus | 2022 | 128GB |
As the table shows, storage capacities have steadily grown over time, from just 4GB on the original iPhone in 2007 to 128GB on recent models like the iPhone 14. Apple typically doubles the storage with each generation. The move to higher minimum capacities allows users to store more photos, videos, apps, and files on their iPhones.
NAND flash storage performance
In addition to increased capacity, NAND flash storage performance in iPhones has also improved substantially over the generations:
- iPhone 4 with NAND flash was up to 10x faster than iPhone 3GS with older NAND flash
- iPhone 5 adopted higher speed LPDDR2 RAM and improved NAND flash, doubling read/write speeds over iPhone 4
- iPhone 6 made the leap to PCIe and NVMe interfaces for up to 4x faster NAND performance
- iPhone 8 switched to faster NVMe SSD controllers and 3D NAND technology
- iPhone 12 brought storage speeds up to 50% faster compared to iPhone 11
Apple also utilizes advanced file systems and software optimizations like improved caching to enhance real-world NAND flash performance on iPhones. As a result, launching and switching between apps, saving photos, opening large files and other storage-intensive operations have become much faster on newer iPhone models.
NAND flash reliability
NAND flash memory provides high reliability for iPhone storage. However, it is not infallible.
NAND flash memory has a finite lifespan and can wear out after extensive long-term use. The cells degrade as data is repeatedly written, erased, and rewritten over time. iPhones use high-endurance NAND flash rated for many tens of thousands of write/erase cycles to maximize longevity.
To further enhance reliability, iPhones employ advanced storage management firmware that equally distributes writes across all NAND flash cells through wear leveling algorithms. This prevents uneven wearing of specific cells.
Error correction code (ECC) is also applied to detect and fix bit errors in stored data that may occur during normal NAND operation. Combined with the inherent resilience of NAND flash, these software protections enable iPhones to provide years of reliable service under normal usage.
Future NAND flash storage trends
As iPhone storage capacities continue to increase, Apple will likely adopt next-generation NAND flash technologies in future models, including:
- QLC NAND – Denser quad-level cell (QLC) NAND increases capacity but has slower write speeds than TLC NAND used today.
- 3D NAND – Stacked layers of flash memory cells provide higher densities without shrinking cell size and loss of performance.
- Z-NAND – Z-dimension nanosheet electrode structure allows higher bit densities and power efficiency.
- CNT NAND – Carbon nanotube filaments replace silicon as charge storage medium, enabling further miniaturization.
- PIM NAND – Processing-in-memory architecture performs operations within the NAND array to reduce data movement.
To offset any tradeoffs from denser NAND technologies, Apple will likely pair them advanced controllers, interfaces, caching, and software optimizations to maintain excellent real-world performance in iPhones.
Conclusion
In summary, iPhones utilize NAND flash memory for internal storage. NAND flash provides iPhones with an optimal combination of performance, reliability, power efficiency, size, and affordability. Starting with just 4GB in the original iPhone in 2007, capacities and speeds have improved tremendously over the generations as NAND flash technology has advanced. Apple will likely adopt new NAND flash innovations like QLC, 3D, and carbon nanotube designs in future iPhones to continue providing an exceptional storage experience.