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Assembly Source File  |  1988-08-11  |  1.2 KB  |  23 lines
  1.         ;************************************************************;
  2.         ;                                                            ;
  3.         ;     Function 0EH: Select Disk                              ;
  4.         ;                                                            ;
  5.         ;     int select_drive(drive_ltr)                            ;
  6.         ;         char drive_ltr;                                    ;
  7.         ;                                                            ;
  8.         ;     Returns number of logical drives present in system.    ;
  9.         ;                                                            ;
  10.         ;************************************************************;
  11.  
  12. cProc   select_drive,PUBLIC
  13. parmB   disk_ltr
  14. cBegin
  15.         mov     dl,disk_ltr     ; Get new drive letter.
  16.         and     dl,not 20h      ; Make sure letter is uppercase.
  17.         sub     dl,'A'          ; Convert drive letter to number,
  18.                                 ; 'A' = 0, 'B' = 1, etc.
  19.         mov     ah,0eh          ; Set function code.
  20.         int     21h             ; Ask MS-DOS to set default drive.
  21.         cbw                     ; Clear high byte of return value.
  22. cEnd
  23.