Changing the I/O Port Address
The setup program, WDTSETUP.EXE, changes the I/O port address that the software uses to communicate with watchdog timer. This address must match the setting of the jumper switches on the watchdog timer. The program updates keys in the registry for the device driver. In order to update these keys under Windows NT Server, the user must be logged in as the administrator or have administrator rights. Windows NT Workstation and Windows 95 allow all users to modify these keys. Under Windows NT, both server and workstation, the changes made by the setup program take effect the next timer the computer is restarted. Under Windows 95, the changes are effective immediately, but any program that is using the watchdog timer when the change is made must be restarted for the changes to take effect.
Disk Caching
Both Windows NT and Windows 95 use disk caching to speed up access of the hard drive. This means that the operating system decides when to write data to the disk instead of it being done when your application writes it. Rebooting the computer with the watchdog timer with
Existing DOS Programs
The NT device driver does not allow existing DOS programs to communicate with the watchdog timer. DOS programs will work under Windows 95, because Windows 95 allows direct access to the I/O ports of the computer.
Windows 3.11
Windows 3.11, just like DOS, allows full access to the I/O ports of the computer, so a simple OUT command can be used to communicate with the watchdog timer. A
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