Looking at both the USB and the storage system of the Xbox, since they are both intertwined and there are differences across the major revisions of the Xbox 360

Background: Xbox Original

To understand the logic of the Xbox 360 storage, you have to look at the past. The original Xbox was one of the first consoles to include an internal hard drive as standard which allowed for storage of game saves, music that could be ripped from an audio CD, or DLC that could be downloaded from Xbox Live. For regular users this meant you did not have to worry about memory cards since the Xbox had plenty of internal storage for game saves and since this was on a hard drive rather than NVRAM like the Sega Saturn, which means saves could be lost should the internal battery die.

The hard drive in the Xbox was one of the more expensive components of the Xbox, and this was one of the reasons the Xbox never made any profit for Microsoft. This had to be addressed with its successor, With this in mind the 360 would be designed over two storage options:

• A basic version that would mirror the storage options of the PlayStation 2/GameCube, where there would be no internal user storage, but an external memory unit would be used instead. The user would still have the option to add a hard drive should they run out of space on the memory unit.

• A premium version that had an internal (or sideloaded) hard drive that brought all the benefits of the hard drive in the original Xbox.

Giving the end-user choice may have been a good idea in hindsight, but there were issues and limitations that followed for both the end-user and the game developers, which will be discussed later.

Type of storage available on the Xbox 360

Xbox Memory Unit: Offered from 2005 – 2010 and was the primary storage option for the initial core and arcade consoles, available in capacities up to 512Mb and designed to be plugged into the front of the 360. Internally uses USB like the original Xbox memory unit. These are not directly compatible with the 360 S models since they lack the ports, third-party adapters are available that allow these old memory units to be used on the S models. Datel are one such provider.

You cannot use an original Xbox memory unit on the 360, or vice versa. Even though they both use USB and are formatted to FATX.

For the early 360 models without a hard drive, the NXE made these memory units mandatory, since portions of the dashboard are now stored on this memory unit since it exceeds the capacity of the onboard flash. The hard drive-equipped models will simply store this on the drive itself.

Further Information

USB Mass Storage: This option was introduced around 2010, before the launch of the S consoles. You can connect a USB memory stick or an external hard drive and use it as additional storage for game saves, DLC or for games themselves (both downloaded and installed from the DVD disc). When first introduced you were limited to 4GB of storage, this was later increased to 16GB, then 32GB and then to 2TB following the release of the Xbox One.

Not all devices can be used, USB flash drives that are not fast enough will not be approved for use, since the Xbox 360 performs a speed test when initializing the storage. This is because some games may malfunction if they cannot access the data fast enough.

Xbox Hard Drive: Generally the most popular form of storage since its fast and easy to set up, but there are some caveats. First was the hard disk design changed from the original models to the S model, whilst the drives are the same internally and could open the case and manually swap the drive over. This is because the hard disk enclosure was redesigned, on the original models the hard drive was connected either on top or on the side depending on the orientation your 360 console was in, whilst the hard drive for the S model was designed to slot inside the console itself.

You cannot use your own hard drive since it has to be formatted and partitioned using Microsoft proprietary format, and Microsoft has not officially released a formatting tool. If you wish to use your own HDD you must softmod the console, or reflash the hard drive itself to make it appear as a Microsoft drive, for which you are limited to 500GB capacity as this was the largest hard disk Microsoft had released for the 360.

The hard drive is the only storage medium that allows for backward compatibility for original Xbox titles, since these games were reliant on using the hard drive for caching and user storage. These games will not run if the Xbox 360 does not have a hard drive. Some third party hard drives can also cause issues as they lack the partition 3 that stored the Xbox emulation and game data, this will need to be restored manually by the user and will allow original Xbox games to save.

Internal Flash storage: This was available for Arcade models released after 2008 that did not come with a hard drive. These models have either 256MB or 512MB of internal storage that was used for the dashboard, which became essentially when the NXE dashboard was released. Memory units and hard drives could still be used for these models. With the release of the 360 S, the 4GB model came with internal storage that was really a USB drive mounted internally to the console, like the Wi-Fi adaptor. This internal storage behaves like the memory unit. Some users have been able to modify and replace this internal storage.

HD-DVD: This addon also came with a built in memory unit, but was designed to be connected to the rear of the console and was intended to store a copy of the HD-DVD movie player.

USB Transfer Cable: Was intended to be used to move contents from one Xbox 360 drive to another but from looking at footage online it seems to appear in the storage section of the dashboard as a ‘Transfer Cable’ but its unknown if the Xbox can store files here directly or if its limited for copying only.

Storage Summary

	Memory Unit	USB Storage	SATA Hard Disk
Capacity	Upto 1GB (512Mb per memory unit, upto 2 can be connected)	Up to 4TB, upto 2 can be connected at once	Upto 500Gb for an unmodified console
Speed	Unknown, less than 480Mbps	Up to 53MB/s (480Mbit/s) shared between different USB devices	Up to 150MB/s (1.5Gbit/s)
Availability	Original models only, S model requires an adaptor	All Models	All Models
Can be used for	Saves, Music, DLC, Apps	Game installs, Saves, Music, DLC, Apps	Game installs, Saves, Music, DLC, Apps

Game Installs: Xbox 360 games can be installed to the hard disc, which allows for faster loading times since hard drives are generally faster than the optical drive, and has the benefit of reducing the wear and tear of the optical drive, and the reduction of heat in the console since the drive can spin down. Thanks to this feature you will want to get the most storage avaliable for your 360, especially if you have a large game library.

It’s worth noting there are some games that are discouraged from being installed this way, such as Halo 3 as that game will cache data to the hard drive regardless, and will load data from both the DD and hard disk simultaneously. It is claimed that installing this to the hard drive would see a reduction in performance (Although the dashboard still lets you install the game). But if you install the game to USB storage instead, the game has access to both the USB image and the cached data on the hard disk, which should yield a noticeable improvement over just running it from the DVD drive. Allegedly this issue was not fixed for the game’s on-demand version, which is downloaded to the Xbox hard drive regardless, you will possibly want to install Halo 3 to USB storage, even if you have plenty of space on it your 360 HDD. Further Information

Maximum Storage: Theoretically the maximum storage for the Xbox 360 is 5.505TB, with a 500GB SATA HDD, two 2TB USB drives/HDD and two 512MB memory units, along with a 4GB internal flash memory assuming a basic S model is being used. I’d say that’s enough for the entire Xbox 360 game library.

USB Ports

The number of USB ports vary on the different models

Launch Consoles

S Consoles

Good idea to run Kinect games off USB storage?

USB has limited bandwidth which is shared across the different devices that are connected, in the case of the S models this included the internal Wi-Fi adaptor. This could potentially cause issues when running games that use the Kinect sensor which uses the USB bus, and a USB external drive. There is a theory below that the Kinect/rear USB port has its own dedicated controller/bus, which gives its own bandwidth.

Are all the USB ports the same?

No, or at least there are certain devices that can only be connected to specific ports:

Kinect – original 360 models: the rear USB port was designed to run on its own bus, intended for a device connected that has the full bandwidth that USB2 can provide which is why Kinect can only be connected to this port for the original models, the other USB ports seem to share bandwidth possibly along with the memory units which was referenced on an online podcast (Major Nelson, sadly the link is no longer active and does not appear in the podcast archives.)

Memory Unit Adaptors

Although the S models lack the memory unit ports on the front, Datel released a USB to memory unit adaptor that was intended to connect a memory unit to a PC to transfer and backup save files. The side effect of this was the memory unit can be used on the S model XBOX 360, despite Microsoft not officially supporting it. However only the front USB ports can be used, and the icon varies depending on which port you connect to. The left USB port appears as Memory Unit A, whilst the right appears as Memory Unit B.

This may mean the USB ports are hardcoded by the kernel and would explain why they do not function on the rear USB ports.

Sample adaptor: eBay, GAME

HD-DVD addon

Microsoft decided to channel the spirit of Sega and released an addon in 2006 to add HD-DVD playback support to the console, but does not allow games to boot from the drive. This is for video only, Microsoft never released games on the HD-DVD format (If only they did, some games took up three dual-layer DVD’s). The drive connects to the console via the rear USB port and features two USB ports on the read of the drive itself, allowing for the wireless adaptor to be mounted and connected to the rear, and a free USB port for another accessory (But not Kinect, since that won’t function behind a USB hub). This drive also features an internal storage device that the user can access and was intended to store the HD-DVD playback software, and possibly any files the HD-DVD disc might save. From this we can conclude there is a four-port hub internal to the drive, one for the drive itself, another for the built-in memory unit and two for the rear USB ports.

Miscellaneous observations

USB: I have noticed some differences in behavior between the front and rear ports of my Xbox 360 S, specifically with USB Memory stick when you turn it on. Sometimes if the flash drives are plugged into the rear and you turn it on, the 360 will not detect or mount the drive and you have to unplug and connect the drive before the 360 will recognize it. This never happens when you leave them plugged into the front. However as of 2021 this seems to have been rectified, so maybe a dashboard update has resolved this issue? Also, the rear USB ports are recessed into the case, and some flash drives might be too thick or large to fit in, which requires a short extension cable.

External Hard Drives: Use of external hard disks is recommended due to the speed and capacity they provide (external SSD’s can also work but will be heavily bottlenecked, and might be limited by the power that USB2 can provide) However I would advise avoiding the cheaper external hard drives that you will see on Amazon or eBay, purely because they are dumb in the sense that they do not spin the disk down when the Xbox 360 is powered off. They will keep the hard disk spinning constantly despite the host device being powered off, wasting electricity and reducing the lifespan of the hard disk if not properly ventilated, essentially they are a false economy. A lot of the branded drives (Western-Digital/Seagate/Samsung) external drives do spin the drive down when the host has powered off and reactivate when they detect the device being powered on.

Some 2.5inch drives and SSDs are capable of being bus-powered, whey they only require the use of a single USB connector to provide power.

Xbox 360 Consoles & SKU’s

Xbox 360 Core: Launch entry level model – No internal flash user storage, no hard drive included but can be added later, memory unit required for NXE update,

Xbox 360 Arcade: Replaced the Core model, No internal user storage, No hard drive included but can be added later, memory unit required for NXE update.

Xbox 360 Arcade (Jasper): Same as previous Arcade model but with 256MB onboard user storage, no hard drive included but can be added later, Can take the NXE update without any additional storage needed, 512MB version later available

Xbox 360 Pro: Launch premium model, Shipped with 20GB/60GB hard drive which is required for it to boot post NXE dashboard, No internal flash user storage

Xbox 360 Elite: Revised premium model, Shipped with 120GB/250GB hard drive which is required for it to boot post NXE dashboard, No internal flash user storage

Models from this point forward are Xbox 360 S

Xbox 360 S: Glossy black case (later matte), Shipped with 250GB/320GB/500GB hard drive storage, No internal flash user storage, Requires hard drive to boot

Xbox 360 S: Matte black case, Shipped with 4GB internal flash memory, No hard drive included but has a bay area for it to be installed, Hard drive not required to boot.

Xbox 360 E: Available in the same storage configurations as the S models (4GB flash or HDD)

NXE Update and storage: Because the size of the dashboard grew significantly with this update, additional storage was required in order for this dashboard to function. All Xbox 360’s have internal onboard flash memory, even the original core models and the ones shipped with a hard drive however this memory cannot be manipulated by the user. They contain 16MB of onboard flash which contains the dashboard kernel itself and the system software which is required for the 360 to operate. This was increased to 256Mb for the later arcade revisions so they could store the NXE update without the need of external storage. This 16Mb flash cannot be accessed directly by the user and was intended to be used for the dashboard itself