PRODUCT  :  TURBO BASIC                                      NUMBER  :  415
  VERSION  :  1.1
   OS  :  DOS
  DATE  :  December 30, 1987                         Page 1/2

  TITLE  :  Free Space on a Disk




  This program demonstrates how to obtain the number of available bytes on a
  disk using the REG and CALL INTERRUPT statements.

  SUB GetFreeSpace(Drive)
    SHARED Sectors,TotalSpace,AvailableSpace

                            ' Load the AH register with 36 hex
    REG 1,&H3600            ' The AL register contains 00

                            ' Load the DX register with the drive designator
    REG 4,Drive             ' 0 = default, 1 = A, etc

    Call Interrupt &H21     ' Invoke function 36 hex

    Sectors = REG(1)        ' sectors-per-allocation unit (cluster)
    FreeAloc = REG(2)       ' number of available clusters
    BytesPerSector = REG(3) ' bytes per sector
    TotalAloc = REG(4)      ' total number of clusters

                            ' calculate the total space on the drive
    TotalSpace = TotalAloc*Sectors*BytesPerSector

                            ' calculate the available space on the drive
    AvailableSpace = FreeAloc*Sectors*BytesPerSector

  END SUB
  Start:
    CLS
    INPUT "Which Drive (<ENTER> for current):",Ans$
    Ans$ = UCASE$(LEFT$(Ans$,1))
    IF Ans$ = "" THEN
       Drive = 0
     ELSE
       Drive = ASC(Ans$) - &H40
    END IF

    Call GetFreeSpace(Drive)
      IF Sectors = -1 THEN         'SECTORS = -1 INDICATES AN
        PRINT "Invalid Drive"      'INVALID DRIVE
        DELAY 2
        GOTO Start
      END IF














  PRODUCT  :  TURBO BASIC                                      NUMBER  :  415
  VERSION  :  1.1
   OS  :  DOS
  DATE  :  December 30, 1987                         Page 1/2

  TITLE  :  Free Space on a Disk




    PRINT "Total size of the disk is ";TotalSpace;"bytes"

    PRINT "Free area on disk is ";AvailableSpace;"bytes"

  END