HDD Led issue, how to make it blink as normal?

blackoil · Post by **blackoil** » Wed Feb 13, 2008 5:03 am

the HDD led is always on, after boot to my os, it doesn't blink when acces harddrive sector. Is there any status bit I should read to acknowledge something?

AJ · Post by AJ » Wed Feb 13, 2008 5:29 am

Hi,

If your OS is loaded from a hard drive, the BIOS may leave it spinning - when you finish with HD access, you need to spin the HD down (after, say, a delay of 500 msec).

Cheers,
Adam

blackoil · Post by **blackoil** » Wed Feb 13, 2008 7:06 am

I boot from floppy.

xyzzy · Post by **xyzzy** » Wed Feb 13, 2008 7:22 am

Most bootloaders (GRUB definitely) don't turn off the floppy motor which will cause the LED to stay on.

Solar · Post by **Solar** » Wed Feb 13, 2008 7:24 am

I noticed similar behaviour when I installed Linux on an Acer laptop recently, so it might not be your fault, not knowing what special tricks Windows has to pull off...

Jef · Post by **Jef** » Wed Feb 13, 2008 5:21 pm

stop floppy motor:

Code: Select all

xor	eax, eax
mov	edx, 03F2h
out	dx, al

start motor:

Code: Select all

mov 	eax, 1Ch
mov 	edx, 3F2h
out 	dx, al

blackoil · Post by **blackoil** » Wed Feb 13, 2008 10:52 pm

I mean the Hard disk led, not the led on the floppy.

I suspect there is a bit in one of ata controller registers, that has to be toggled.

The led indicates whether the harddisk is busy or not.

I can't find any related references in T13 ocuments.