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Index > OS Construction > int 13 extended write hanging

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Spinlock



Joined: 03 Mar 2008
Posts: 2
Spinlock
I'm trying to run extended write (int 13h, ah=48h) in my boot sector to a USB flash drive (which I booted off of, which is reporting as device 80h). I can correctly read the drive's metrics and see that it supports extensions (30h), but when I call the write function (lba 1) it just hangs indefinitely. I've run the code in qemu with the bootsector (plus some padding to write to) as a fake hd image and it's worked there. Any help would be appreciated.
Post 03 Mar 2008, 22:34
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edfed



Joined: 20 Feb 2006
Posts: 4242
Location: 2018
edfed
try to identify the drive.
before to read from a drive with lba, you must convert lba to chs and use int13h as if the drive was chs.
if extended don't works, try the old method.

it works on my pcs.
see on yours.
Post 03 Mar 2008, 22:46
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Spinlock



Joined: 03 Mar 2008
Posts: 2
Spinlock
I thought since I was just trying to write to the second sector lba=chs=1. Is this wrong?

Further, I need to write to the whole 4gb, so I believe I need the extensions. I guess I'll try the non-extended write when I get home to see if that stalls too, but it won't be enough if I can't write to the full 4gb Sad
Post 03 Mar 2008, 22:58
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edfed



Joined: 20 Feb 2006
Posts: 4242
Location: 2018
edfed
chs can access be up to 8G drives.
lba 0 = chs 0/0/1
Post 03 Mar 2008, 23:39
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