Current control set
The Windows Registry contains the Current control set key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet
Current Control Set - Windows 9x/Me
In Windows 9x/Me the Current Control Set key is stored in the SYSTEM.DAT Registry file.
Current Control Set - Windows NT
On Windows NT the Current Control Set key is only present at run-time. The contents of the key is stored in the SYSTEM Registry file and can be determined by reading the Current value from the key:
<RootKey>\Select
The Current value contains number of the current control set. Normally 1 or 2 but other values like 3 or 47 are known to be used. For example a value of 1 maps to the Control Set key:
<RootKey>\ControlSet001
Normally there are multiple Control Set keys the role each of the Control Set keys can be different:
ControlSet001 may be the last control set you booted with, while ControlSet002 could be what is known as the last known good control set, or the control set that last successfully booted Windows.
These roles are defined by the other values in the Select key:
| Name | Data type | Description |
|---|---|---|
| Current | REG_DWORD | Current Control Set |
| Default | REG_DWORD | Default Control Set |
| Failed | REG_DWORD | Control Set that failed to boot |
| LastKnownGood | REG_DWORD | Last known good Control Set |
Notes
Determine if a value of 0 indicates not set
Confirm if speculations that 9 is the largest value ControlSet00#