There are many technical documents on this page Intel® Atom™ Processor E3800 Product Family (Formerly Bay Trail). Scroll farther down the page to the 'Technical Documents' and the 'Tools & Downloads' sections. Many of these documents are classified as Intel Confidential which requires a non-disclosure agreement between your company and Intel. You would need to request an 'upgrade to Privileged' account request by visiting your profile page on Intel.com. You can find more information in the "Manage my Account" section found on this page: Intel® Embedded Design Center Contact and Support. However, to qualify for an account, you must use a company email address, not a personal one such as yahoo, gmail, qq, etc. If you would like to be contacted by an Intel representative to assist you in this process, please let me know. Thanks! LynnZ
For Windows 7 the Developer Manual comes in the zip file with the Embedded Drivers for Windows 7 that can be freely downloaded from here: https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=24548&lang=eng
For Windows 8.1 the Developer Manual is still considered Intel Confidential, so you would need to get a CNDA agreement with Intel to obtain them.
Since you don’t have a CNDA in place yet I can give you the following suggestions/resources
You can download the Intel embedded drivers for Windows 8.1 in the following page: https://downloadcenter.intel.com/SearchResult.aspx?lang=eng&keyword=bay+trail
Once installed you can check the Microsoft resources for Developing GPIO drivers in the following links (there you can find source code examples that might be useful to you):
You should also check chapter 39 PCU-iLB-GPIO of the Bay Trail Datasheet: Intel® Atom™ Processor E3800: Datasheet
I hope this is useful to you.