Contributor: ERWIN PAGUIO
{
The returned value of FirstDrive is an unsigned integer where 0 = 'A', 1 = 'B',
and so on. So to get the actual drive letter you use:
FirstDriveLetter := Chr(FirstDrive + Ord('A'));
LastDriveLetter := Chr(FirstDrive + NumDrives + Ord('A'));
}
Function CheckCDROMDrives(Var FirstDrive, NumDrives : Word):Boolean;Assembler;
ASM
XOR BX, BX { zero out BX to check availability of function }
MOV AX, 1500h { get no. of CDROM drive letters }
INT 2Fh { BX = count, CX = first }
OR BX, BX { was BX modified? }
JZ @Error { if not, then no MSCDEX driver installed }
LES DI, FirstDrive
MOV ES:[DI], CX { device number of first drive }
LES DI, NumDrives
MOV ES:[DI], BX { number of CD drives }
MOV AL, Byte(True)
JMP @Exit
@Error:
XOR AX, AX
LES DI, FirstDrive
MOV ES:[DI], AX
LES DI, NumDrives
MOV ES:[DI], AX
MOV AL, Byte(False)
@Exit:
End;