Search notes:

Registry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment

Reading values with PowerShell

PowerShell allows to access the values under this key with 
PS> echo [environment]::getEnvironmentVariable("PATH", "machine" )
PS> [environment]::setEnvironmentVariable("ANOTHER_VAR", "another value", "machine")

PROCESSOR_ARCHITECTURE

PROCESSOR_ARCHITECTURE can be used to determine the bitness of the CPU. If it contains x86 (or even x86 Family), it's a 32 bit processor, if it contains 64 Family, it's a 64 bit processor.
The range of values of PROCESSOR_ARCHITECTURE is
Note, 32 bit applications running on 64 bit Windows (WOW64) seem to overwrite this variable in the process (not in the registry) with x86.

See also

Registry: environment variables, HKEY_CURRENT_USER\Environment

Index

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php:78 Stack trace: #0 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(78): PDOStatement->execute(Array) #1 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(30): insert_webrequest_('/notes/Windows/...', 1788275383, '216.73.217.21', 'Mozilla/5.0 App...', NULL) #2 /home/httpd/vhosts/renenyffenegger.ch/httpsdocs/notes/Windows/registry/tree/HKEY_LOCAL_MACHINE/System/CurrentControlSet/Control/Session-Manager/Environment/index(56): insert_webrequest() #3 {main} thrown in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php on line 78