Hey there, The SysFx document on developing APOs states: All code and data in the process path must be nonpageable. The Windows Vista SDK contains a new code- and memory-locking API that is useful for this purpose. For details, see Nturtl.h. I'm having a hard time finding documentation on these new memory-locking functions or the above-mentioned header, and the sample APO doesn't allocate any memory. Does anyone have pointers to these new functions, documentation, and/or sample code? Thanks, -andrew ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/