>>>>> Pavel Roskin writes:
PR> I have found that Stage 2 does an additional check that fails for
PR> that old AmiBIOS. After calling int 0x13 with %ah=0x41 Stage 2
PR> checks %cx If it is 0xFFFF, LBA is not used
Actually, no. If bit 0 of %cx is 0, LBA is not used.
PR> (why? I'll try to find the specification)
See the below `API subset support bitmap' description to see why we
need andw $1, %cx to be nonzero before we use subfunction 0x42.
>From Ralf Brown's interrupt list:
--------d-1341--BX55AA-----------------------
INT 13 - IBM/MS INT 13 Extensions - INSTALLATION CHECK
AH = 41h
BX = 55AAh
DL = drive (80h-FFh)
Return: CF set on error (extensions not supported)
AH = 01h (invalid function)
CF clear if successful
BX = AA55h if installed
AH = major version of extensions
01h = 1.x
20h = 2.0 / EDD-1.0
21h = 2.1 / EDD-1.1
30h = EDD-3.0
AL = internal use
CX = API subset support bitmap (see #00271)
DH = extension version (v2.0+ ??? -- not present in 1.x)
Note: the Phoenix Enhanced Disk Drive Specification v1.0 uses version 2.0 of
the INT 13 Extensions API
SeeAlso: AH=42h"INT 13 Ext",AH=48h"INT 13 Ext"
Bitfields for IBM/MS INT 13 Extensions API support bitmap:
Bit(s) Description (Table 00271)
0 extended disk access functions (AH=42h-44h,47h,48h) supported
1 removable drive controller functions (AH=45h,46h,48h,49h,INT 15/AH=52h)
supported
2 enhanced disk drive (EDD) functions (AH=48h,AH=4Eh) supported
extended drive parameter table is valid (see #00273,#00278)
3-15 reserved (0)
--
Gordon Matzigkeit <[EMAIL PROTECTED]> //\ I'm a FIG (http://www.fig.org/)
Committed to freedom and diversity \// I use GNU (http://www.gnu.org/)
