Microsoft executive Steven Sinofsky today outlined what developers and users can expect from Windows 8 on ARM (WOA) devices.
Microsot plans to release Windows 8 in x86/64 and ARM
devices. We have summarized the basic facts of the WOA experience.
Microsoft says that using WOA "out of the box" will
feel just like using Windows 8 on x86/64. Signing in,
running apps, accessing the new Windows Store (apps)
the start screen, the Metro style apps, the Internet
Explorer and the Windows desktop will be the same, as
the Windows 8 in x86/64.
The company plans to ship WOA PCs at the same time as
PCs designed for Windows 8 on x86/64. These PCs will
be built on hardware platforms provided by NVIDIA,
Qualcomm, and Texas Instruments, with a common Windows
on ARM OS foundation - all running the same Windows OS
binaries - a unique approach for the industry.
Metro style apps found in Microsoft's Windows Store
will support both WOA and Windows 8 on x86/64.
Developers wishing to target WOA will do so by writing
applications for the WinRT (Windows APIs for building
Metro style apps) using the new Visual Studio 11 tools
in a variety of languages, including C#/VB/XAML and
Jscript/ HTML5. Native code targeting WinRT is also
supported using C and C++, which can be targeted
across architectures and distributed through the
Windows Store. WOA does not support running,
emulating, or porting existing x86/64 desktop apps.
Code that uses only system or OS services from WinRT
can be used within an app and distributed through the
Windows Store for both WOA and x86/64. Users will
obtain all software, including device drivers, through
the Windows Store and Microsoft Update or Windows
Update, Microsoft said.
WOA will support all new Metro style apps, including
apps from Microsoft for mail, calendaring, contacts,
photos, and storage. WOA also includes support for
hardware-accelerated HTML5 with Internet Explorer 10.
WOA will also provide support for other
industry-standard media formats, including those with
hardware acceleration and offloading computation, and
industry-standard document formats. WOA includes
desktop versions of the new Microsoft Word, Excel,
PowerPoint, and OneNote. These new Office
applications, codenamed "Office 15", have been
architected for both touch and minimized
power/resource consumption, while also being
fully-featured for users and providing complete
document compatibility. WOA supports the Windows
desktop experience including File Explorer, Internet
Explorer 10 for the desktop, and most other intrinsic
Windows desktop features - which have been architected
for both touch and minimized power/resource
consumption.
Microsoft's partners will provide WOA PCs as
integrated, end-to-end products that include hardware,
firmware, and Windows on ARM software. Windows on ARM
software will not be sold or distributed independent
of a new WOA PC.
Around the next milestone release of Windows 8 on
x86/64, Microsoft will provide a limited number of
test PCs to developers in a closed, invitation-only
program. These are tools for hardware and software
engineers running WOA-specific hardware. The Windows
Consumer Preview, the beta of Windows 8 on x86/64,
will be available for download by the end of February.
WOA will also include the Windows desktop, which
offers users a familiar place to interact with PCs,
particularly files, storage, and networking, as well
as a range of peripherals. Users will be able to use
Windows Explorer, for example, to connect to external
storage devices, transfer and manage files from a
network share, or use multiple displays, and do all of
this with or without an attached keyboard and mouse.
They'll have access to a deep array of control panel
settings to customize and access a finer-grained level
of control over their system.
At the same time, WOA (as with Windows 8) is designed
so that users focused on Metro style apps don't need
to spend time in the desktop.
One of the new aspects of WOA is that it will not
turn off a WOA PC. WOA PCs will not have the
traditional hibernate and sleep options with which we
are familiar. Instead, WOA PCs always operate in the
newly designed Connected Standby power mode, similar
to the way we are using in a mobile phone today. When
the screen is on, users have access to the full power
and capabilities of the WOA PC. When the screen goes
dark (by pressing the power button or timer), the PC
enters a new, very low-power mode that enables the
battery to last for weeks. For end-users, a new
capability of WOA is that they are in control of what
programs have access to background execution so that
those apps are always connected, and information like
new mail is always up to date. Connected Standby
permeates the engineering for WOA PCs from the
hardware through the firmware, OS, WinRT platform, and
apps. Connected Standby won't be limited to the ARM
architecture and Microsoft is working on these
capabilities for x86/64 SoC products as well.
By design, ARM systems are not standardized - each
device from each manufacturer is unique and the
software that runs on that device is unique. There is
of course a standard instruction set and CPU
architecture, but many of the connections between the
CPU and other components are part of the innovation
each licensee brings to the ARM platform. End-users
will be technically restricted from installing a
different OS (or OS version) on a device or extending
the OS, so this is generally not possible, and rarely
supported by the device maker. Device makers work with
ARM partners to create a device that is strictly
paired with a specific set of software (and sometimes
vice versa), and consumers purchase this complete
package, which is then serviced and updated through a
single pipeline. In these ways, this is all quite
different than the Windows on x86/64 world.
Microsoft's device strategy uses standardized
protocols and class drivers extensively:
- Low power serial busses such as I2C / UART will be
normal on ARM PCs and less common on x86 PCs.
- SD I/O will allow users to connect low power Wi-Fi
radios. Radios in current PCs are connected via USB or
PCI-E. Microsoft added SD I/O support to preserve high
data rates (100 MB/s) while still improving battery
life. Wi-Fi support on WOA also allows efficient
offloading to maintain connections in connected
standby while using very little power.
- Embedded MultiMediaCard storage (eMMC) is a de facto
standard for storage on ARM devices (since most do not
support SATA). In addition to supporting eMMC,
Microsoft made several OS performance optimizations
to reduce and coalesce storage I/O, resulting in fewer
reads and writes to storage.
- The General Purpose I/O (GPIO) driver supports
connecting buttons, interrupts or other I/O to the ARM
processor. In addition to the GPIO driver, there?s
also a button driver for the Windows, power, and
volume buttons.
ARM SoCs for WOA will also have DirectX capable GPUs (DX)
for accelerated graphics in Internet Explorer 10, in
the user interface of Windows, and in Metro style
apps.
WOA PCs use hardware support for offloading
specific work from the main processor to integrated
hardware subsystems. This improves performance and
battery life. For example, while watching a movie, the
processing is done with multimedia offload (to a
dedicated processor for example), and all other
processing is minimized.
The services that will support the full breadth of
Windows are common across the architectures, so that
developers can take advantage of them in Metro style
apps:
- Mobile broadband (MBB) class driver. By creating a
class driver, Microsoft made it much easier to add
broadband capability to all Windows PCs.
- Printer class driver. For Windows 8, Microsoft
rearchitected the print infrastructure to add class
driver support. The majority of printers selling today
are supported using the class driver, which means
users will be able to "plug and print" on WOA without
additional drivers.
- GPS. Windows offers a location provider that can
triangulate a PC's location via Wi-Fi access points
and a backing database. In addition, systems that have
Mobile Broadband will also have integrated Global
Navigation Satellite System (GNSS, aka GPS in the US)
receivers to provide accurate location while
navigating outdoors.
- Sensors (accelerometer, rotation, gyro, compass,
magnetometer). Mirosoft has added support for sensors
in SoC-based architectures and utilizes the HID over
I2C protocol.
- Bluetooth. WOA supports Bluetooth LE and the same
profiles as Windows 8 on x86/64 and connectivity to
the Bluetooth radio using low-power UART.
- MTP over USB and IP. Windows on ARM provides users
with the ability to connect their portable devices
(like mobile phones, music players, cameras) to their
systems using the Media Transfer Protocol (MTP). These
MTP-compliant devices can connect over USB or IP by
leveraging inbox Windows class drivers, and allow
users to exchange data with their favorite Metro style
apps.
- Windows Update-based servicing. For all platform
code (OS, drivers, system and device firmware), each
WOA system will be serviced through Windows Update
(WU), from top to bottom. Microsoft has added support
in WU for updating the system firmware on WOA systems,
as well as driver targeting, which means that each
device will get the drivers that have been verified to
work best with it.
Previously Microsoft has detailed that WOA will not
support any type of virtualization or emulation
approach, and will not enable existing x86/64
applications to be ported or run.
"If you need to run existing x86/64 software, then you
will be best served with Windows 8 on x86/64. If
you're already considering a non-Windows device, then
we think WOA will be an even better alternative when
you consider the potential of form factors,
peripherals, Windows Store apps (and developer
platform), and Office applications as well as a broad
set of intrinsic Windows capabilities," Microsoft
said.
Developers wanting to reach WOA with existing apps
will have two options. Many apps will be best served
by building new Metro style front ends for existing
data sources or applications, and communicating
through a web services API. Of course, these do not
need to be just front-ends, but could operate on local
data too, since WOA provides full access to files and
peripherals. Other existing applications will be
served by reusing large amounts of engine or runtime
code, and surrounding that with a Metro style
experience.
WOA PCs will be serviced only through Windows or
Microsoft Update, and consumer apps will only come
from the Windows Store, so users never have to worry
if a program will run because they are not downloading
or installing from a DVD outside of the store
experience.