Embedded Windows

Windows Embedded POSReady 7: The Right Choice for Digital Signage

Digital signage is a burgeoning embedded market with unique systems needs. A specially tuned version of Windows Embedded can help developers meet the interactive, connected demands found in the retail space.


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On July 1, 2011, Microsoft released their newest Embedded Operating System, POSReady 7. The previous versions of POSReady were well accepted and hold a dominant marketshare position within cash registers and other point-of-sale systems. It’s not surprising then that most OEMs assume that the POS in POSReady stands for “point of sale.” However, Microsoft views this acronym differently and redefines POS as “point of service.” This distinction opens the door for POSReady to be used in a broader range of embedded systems.

In its “Additional Licensing Terms” (ALTs), Microsoft specifies where POSReady 7 can be used. The ALTs define the distribution rights and restrictions specific to the different Microsoft Embedded Operating Systems. Within the ten pages of POSReady 7’s ALTs, a section states that this operating system can be used in embedded systems for:


• Digital signage

• Recording and/or transmitting customer information

• Information and transaction kiosks

• Providing information to customers on the availability of products and services

• Sales and services transaction processing

• Scanning and tracking inventory

There is a lot more information in the ALTs, but it is noteworthy that the ALTs explicitly list digital signage, one of the fastest growing verticals in the electronics industry. According to Digital Signage Today, the global market for digital signage will grow from nearly $1.3 billion in 2010 to almost $4.5 billion in 2016.

Putting aside the name issue, and with a better understanding of where it can be used, we can now dig into what makes POSReady 7 a desirable product for digital signage.

First, there is the bottom line—cost. POSReady 7 costs around $100. The typical non-embedded alternative to POSReady 7 would be Windows 7 Professional OEM, which costs around $135 per runtime license, and Windows 7 Ultimate OEM runs at around $180.

Feature-wise, POSReady 7 aligns most closely with Windows 7 Ultimate. One of the features POSReady 7 and Windows 7 Ultimate have in common is DirectAccess. DirectAccess acts like an automatic and always-on virtual private network (VPN). When a client device with DirectAccess connects to the Internet, it automatically makes a secure connection to the OEM’s server. Unlike a VPN, DirectAccess enables a remote system to boot up and connect with the server unattended. It can then be managed and receive content and exchange encrypted data with the server.

This is critical for the digital signage market because secure, encrypted communication has become more important as digital signs have moved on beyond just indiscriminately displaying content. Digital signage systems are now able to gather information about the user, and the user is able to interact more with the system. At the 2011 National Retail Federation show in New York, people crowded the Microsoft booth when they found out that the booth had camera-equipped systems that identified the gender and approximate age of people as they entered the booth. The system was uncanny in its accuracy. Imagine a sign presenting content customized to each user’s demographic and the user being able to interact via touch screen or a Kinect detected gesture to gather specific information, or even make a purchase using a near-field communication (NFC) equipped phone.

Beyond the advanced features found in Windows 7 Ultimate, POSReady 7 has some valuable features that are only available in Microsoft embedded operating systems known as “Embedded Enabling Features” (EEFs). Two of the most noteworthy EEFs are “Enhanced Write Filtering” (EWF) and “Hibernate Once Resume Many” (HORM).

Digital signs are typically turned off by cutting the power. Virtually everyone knows not to turn off an office desktop system by pulling the plug. On a running system, there’s chatter between the operating system and the hard drive, and a power failure can cause an interrupted write-in-progress to corrupt a file that is vital to the operating system. Unlike an office desktop PC, digital signage systems are almost always systems that are remotely managed, without someone at the system hooked up with an extra monitor, mouse and keyboard who can signal the system to gracefully shut down.


The challenge is how to prevent power outages from corrupting the operating system on a digital sign. The answer is EWF, an EEF in POSReady 7 (Figure 1).

Figure 1
Enhanced Write Filter (EWF) is an upper filter driver in the volume stack. It is located between file systems and the class drivers that interface with physical disks.

EWF uses a RAM overlay as a substitute for the boot volume. By using EWF, the boot volume becomes read-only and never changes. At power down, any changes recorded in the RAM overlay are lost with the boot volume reverting back to the settings from when the system was last booted. EWF management tools make it possible to permanently change the boot volume either by turning off EWF before the next boot, or by performing a “live commit” command (Figure 2).

Figure 2
EWF uses a RAM overlay to prevent the boot volume of the hard drive from being written to. This prevents OS corruption that can happen during abrupt power failures. It also allows for Hibernate Once Resume Many (HORM).


Another EEF made possible with EWF is Hibernate Once Resume Many (HORM). While office desktop and laptop users are accustomed to having to wait a few minutes for the system to “wake-up,” people turning on digital signs expect them to function within seconds after the power is turned on. Hibernate Once Resume Many is much like the hibernate function on a laptop. When you put a laptop into hibernation, it creates a snapshot of what is running into a “hiberfile” before shutting down. Then at boot-up, the hiberfile is used to bypass the typical lengthy cold-start boot process. Since the EWF volume never changes, it can have a ready-made hiberfile allowing it to boot quickly. Unlike most systems that boot slower and slower over time, the boot time never changes.

EWF can protect the boot volume from getting corrupted from unexpected power outages, but it raises a question about remote management. How can system administrators update or even replace the boot volume remotely if the changes only go into a RAM overlay and are lost during the next power cycle? With this in mind, Microsoft introduced Windows Embedded Device Manager 2011 (WEDM). WEDM consists of client software that can be added to POSReady 7 or Windows Embedded Standard systems, and a server plug-in that installs into the System Center Configuration Manager (SCCM) 2007.

Virtually anyone who is connected to a corporate network is familiar with how their system is managed over the network. Software updates and operating system policies are often managed using SCCM as the “Single Pane of Glass Management” solution. Without the Windows Embedded Device Manager plug-in, systems with embedded operating systems are undifferentiated from the other non-embedded desktops or laptops on the network. With WEDM installed on both client and server, the clients with the embedded operating systems are recognized and can be placed into specific Windows Embedded device collections, aggregating similar devices into manageable groups, such as digital signs. The WEDM plug-in has tools that allow the system administrator to remotely turn on and off write filtering to make permanent changes to the remote systems, including the ability to re-image the device entirely.


POSReady 7 also has an EEF called “Dialog Box Filter” that can prevent dialogs or unwanted windows from popping up on the screen by pre-assigning an action to be taken on an anticipated box button before it even gets to the screen. If the system pictured in Figure 3 had been using POSReady 7 with the dialog box filter, this pop-up would have been intercepted and answered before it even appeared on the screen.

Figure 3
Customers interacting with digital signage do not need to see system dialog boxes that may appear on the display. A method for predefining actions that may be taken on system exceptions will prevent their appearance in the retail environment.

POSReady 7 also works well for digital signage because it does not require activation. When non-embedded versions of XP or Windows 7 are installed on a computer for the first time, the installation requires the installer to type in a string of 25 letters and numbers known as a Product ID (PID) or activation key. After the system starts and connects to the Internet, that PID and information unique to the hardware on which the operating system is installed is sent to Microsoft and the operating system becomes permanently “unlocked.” If the PID was used before on another system, it does not “unlock,” and the operating system will fail to operate. With POSReady 7 and Windows Embedded Standard 7, a single activation key can be obtained from Microsoft that can be pre-installed into the system’s image. The configured operating system can then be loaded “unlocked” onto any number of systems, and they will never have to be individually activated. This is extremely helpful when you are managing thousands of signs across hundreds of locations.

While POSReady 7 has a solid feature set for digital signage, there are also some alternatives to it if this full of a feature set is not needed or if cost is a factor. Windows Embedded Standard 7 (WES7) has all the EEFs of POSReady 7. This componentized version of Windows 7 requires a $995 software toolkit for OEMs to create a unique image that can be scaled in size and functionality. Because POSReady 7 is not componentized, it can be installed directly onto a system without having to purchase a toolkit. The “E” version of WES7 is around $90 per runtime, $10 less than POSReady 7. The “E” version of WES7 does not have the advanced security features, including DirectAccess found in Windows 7 Ultimate and POSReady 7. Nor does the “E” version have Multi-touch for pinch and zoom, an advanced touch feature popularized on many smartphones. If individual runtime cost is the primary concern, and the sign does not need DirectAccess or Multi-touch, WES7 E might be a lower cost alternative.

OEMs interested in incorporating POSReady 7 into their digital signage solution will find that the Windows Embedded products are much more restricted in their distribution. Any OEM wanting to purchase POSReady 7 or any other Microsoft Embedded Operating System is required to sign an OEM Customer License Agreement (CLA) with Microsoft. The primary purpose of the CLA is to make sure that embedded runtime licenses do not wind up on systems that could be used as general-purpose PCs. Simply put, Microsoft doesn’t want their lower cost, longer life embedded products cannibalizing their high volume general purpose PC operating system sales. OEMs can get the CLA and ALTs for Microsoft Embedded products through the Microsoft Embedded distributors. 



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