protect RTC password?

[a5498828]

ive been trying to learn what bit 3 of port 0x92 is used for. As i understand, it blocks access to few bytes in cmos memory that contain password hash.
Ive tried setting this bit, then reading entire cmos memory, and there is no diffrence. I get the password hash all the itmes.

Is it some sort of legace or what? Ive googled much about it, found that people have problem because 'pasword is not reset when i pull the battery'.
My conclusion is that this bit might have an effect, or the password is written in eeprom. Is that possible, what bios write password in eeprom on some machines?

Code: Select all

0092	r/w	PS/2 system control port A  (port B is at 0061)
		 bit 7-6   any bit set to 1 turns activity light on
		 bit 5	   reserved
		 bit 4 = 1 watchdog timout occurred 
		 bit 3 = 0 RTC/CMOS security lock (on password area) unlocked
		       = 1 CMOS locked (done by POST)
		 bit 2	   reserved
		 bit 1 = 1 indicates A20 active
		 bit 0 = 0 system reset or write
			 1 pulse alternate reset pin (alternate CPU reset)

[Tosi]

Since that is the PS/2 control port, it will not work on earlier PCs and might work on later ones. Are you testing on a PS/2?
The reference you have also says that bit 3 is set by POST, which I would interpret as a recommendation not to mess with it unless I was writing a BIOS.