Autor: Darek Grzegorski (darq_at_bull.mimuw.edu.pl)
Data: Tue 16 Jan 1996 - 19:07:36 MET
On 16 Jan 1996, Stanislaw Jedrus wrote:
[...]
> problemu). I przestawiajac tryb w bios-ie na LBA powodujemy, ze jesli
> wpiszemy geometrie inna od rzeczywistej to jest ona konwertowana.
> Najciekawsze w tym wszystkim jest to, ze u kumpla ktory ma bios okienkowy
> formatowanie musialo sie odbyc na zmienionej geometrii a uzytkuje go
> na zwyczajnej wiec cyrk jest nieziemski. Tego to ja juz wyjasnic nie moge
> wiec moze ktos wie cos wiecej na ten temat?
>
Ktos kiedys na tej liscie podal namiar na informacje o EIDE, LBA i innych
takich: http://www.wi.leidenuniv.nl/ata/
Jest tam dostepny tekst o sposobach translacji L-CHS/P-CHS/LBA oraz o typach
BIOS-ow, fragment przytaczam ponizej:
BIOS Type 7
Origin: Described in the Western Digital Enhanced IDE Implementation
Guide.
BIOS call support: INT 13H AH=0xH and FDPT or EDPT for BIOS drives 80H
and 81H. An EDPT with a L-CHS of 16 heads and 63 sectors is built when
"LBA mode" is enabled. An FDPT is built when "LBA mode" is disabled.
! Description: Supports >1024 cylinders or >528MB using a EDPT with a
translated CHS *** BUT ONLY IF *** the user requests "LBA mode" in the
BIOS setup *** AND *** the drive supports LBA. As long as "LBA mode"
is enabled, CHS translation is enabled using a L-CHS with ! When "LBA
mode" is disabled, this BIOS looks like a BIOS type 2 with an FDPT.
The L-CHS used is taken either from the BIOS drive type table or from
the device's Identify Device data. This L-CHS can be very different
from the L-CHS returned when "LBA mode" is enabled.
This BIOS may support FDPT/EDPT for up to four drives in the same
manner as described in BIOS type 4.
! The basic problem with this BIOS is that the CHS returned by INT 13H
AH=08H changes because of a change in the "LBA mode" setting in the
BIOS setup. This should not happen. This use or non-use of LBA at the
ATA interface should have no effect on the CHS returned by INT 13H
AH=08H. This is the only BIOS type know to have this problem.
! Support issues: If the user changes the "LBA mode" setting in BIOS
setup, INT 13H AH=08H and the FDPT/EDPT change which may cause ***
DATA CORRUPTION ***. The user should be warned to not change the "LBA
mode" setting in BIOS setup once the drive has been partitioned and
software installed. Different CHS translation algorithms may be used
by the BIOS and an OS.
Zatem rzeczywiscie w takich BIOS-ach wlaczenie konwersji CHS jest zwiazane
z wlaczeniem odwolan do dysku w trybie LBA, a nie jak sadzilem robione
zawsze. Ale tez jak widac adresy logiczne moga, ale NIE MUSZA sie roznic
od fizycznych - wszystko zalezy od ich translacji, ktory nie jest rzecza
zestandaryzowana.
--
(~~ (^# ~~~~~~~~~~~~~~~~~~~~~~~~~,~~~~~T~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #^) ~~)
| \ /^--^\ Darek Grzegorski | student of MISMaP /^--^\ / |
| { O @ } darq_at_bull.mimuw.edu.pl | darq_at_chem.uw.edu.pl { @ O } |
| ( \__/ ) http://bull.mimuw.edu.pl/~darq ( \__/ ) |
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To archiwum zostało wygenerowane przez hypermail 2.1.7 : Tue 18 May 2004 - 12:38:36 MET DST