Int 15/AH=E4h

Compaq ROM BIOS 1993/08/03 and newer - ???

AH = E4h
AL = subfunction
00h get advanced system info
Return:
CF clear
AH = 00h
CX = 0000h
BX = advanced system info flags (read from [XBDA:0094h])
bit 4:
"mode 2" (dual harddisk controller) enabled
01h,02h unsupported by this ROM version
Return:
CF set, AH = 86h
80h set advanced system info
BX = advanced system info flags
bit 4:
Enable "mode 2" (dual harddisk controller)
???
Return:
???

Note: On Compaq machines with "COMPAQ" signature at F000h:FFEAh (see also MEM F000h:FFE0h), MS-DOS/PC DOS IO.SYS/IBMBIO.COM use this function to set bit 4 before calling INT 13h/AH=08h to retrieve the number of hard disks installed (DL). 90h,A0h,B0h,C0h,D0h,E0h,F0h set ???

Return:
CF clear
AH = 00h
CX = 0000h
BX = ???
81h,91h,A1h,B1h,C1h,D1h,E1h,F1h unsupported by 3/8/93&4/8/93 ROMs
Return:
CF set, AH = 86h

Notes: Functions 80h/90h/etc. are not supported by the 4/8/93 EISA System ROM. These functions are not supported by the 7/26/93 LTE Lite 386 ROM

Category: Vendor-specific BIOS Extensions - Int 15h - C

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