Self-checkout Machines, Portable EKG devices and Windows Audio

wdkblog — Mon, 29 Jun 2009 02:06:00 GMT

So I was about to start using a self-checkout machine in a grocery store when service tech asked me to use the next one over, so he could service the one I was about to use. I obliged and he proceeded to work his magic. After he was done, he rebooted the machine and to my surprise and I saw the familiar Windows XP boot screen. The boot sequence was quiet with no fanfare and no other sounds.

Two days later, I was waiting for test results in the lab at my primary care clinic and noticed a laptop on a cart. The laptop had a USB device plugged into it, with what seemed like a ton of electrodes connected to the other end of the USB device. I went over to investigate and noticed that the laptop was running (you guessed it) Windows XP and the USB device had a label that indicated that it was an EKG device.

These two close encounters with Windows XP showed the versatility of this operating system. I was also left with a new appreciation for one of the topics that I just completed to describe a new feature that that has been added to Widows 7.

A new registry key, PKEY_AudioDevice_NeverSetAsDefaultEndpoint, has been added to Windows 7 to allow you to configure certain devices (like the portable EKG device, for example) so that they can never be selected as default audio devices. Say for example, that a service tech forgets to reverse audio settings he made while servicing the portable EKG device. It would be very unprofessional to boot up this EKG device later on in a hospital room and have to wait a few minutes while Windows XP initialized Media Player and then proceeded to apply the latest skins, in preparation to play music through the beeper in the EKG device!

In Windows 7 and later versions of Windows, this would be a non-issue because if the laptop were running Windows 7, as soon as you rebooted the laptop, it would apply the default settings and undo the previous selection of the EKG device as the default audio device.

The topic with more information about PKEY_AudioDevice_NeverSetAsDefaultEndpoint will be available on MSDN in the next month.

－ Eric Doku [MSFT], WDK Programming Writer

Announcement: New Features for Registry Callbacks for Vista SP2

wdkblog — Wed, 24 Dec 2008 11:59:00 GMT

Microsoft developers have upgraded and improved the Registry Callback feature of the Windows Driver Model (WDM). They have added 6 enumerations and 3 structures to the kernel architecture that will give you more flexibility in working with registry keys for filter drivers. This new capability was added to Vista Service Pack 2 (SP2) at the last minute and was not covered in the original doc release. Now we can tell you about it because the updated header has just been made available on Microsoft Connect. We wanted to publish this special announcement, so you can make use of this new technology right away.

The 6 new enumerations are:

· RegNtPreRestoreKey

· RegNtPostRestoreKey

· RegNtPreSaveKey

· RegNtPostSaveKey

· RegNtPreReplaceKey

· RegNtPostReplaceKey

The 3 new structures are:

· REG_RESTORE_KEY_INFORMATION

· REG_SAVE_KEY_INFORMATION

· REG_REPLACE_KEY_INFORMATION

Detailed technical information can be found in the following WDK kernel reference topics:

· Registry Callback – the new enumerations are listed in this topic.

· REG_NOTIFY_CLASS – this topic defines the enumerations.

· The new structure topics are:

- REG_RESTORE_KEY_INFORMATION

- REG_SAVE_KEY_INFORMATION

- REG_REPLACE_KEY_INFORMATION

These new features are available in the WDK docs on MSDN.

— Seth McEvoy, [MSFT], WDK Programming Writer

Windows Driver Kit (WDK) Documentation Blog : registry

Self-checkout Machines, Portable EKG devices and Windows Audio

Announcement: New Features for Registry Callbacks for Vista SP2