Hi Martin,

After much fiddling about (and some advice from David Milton) I've
managed to refine the code so that it obtains both the boot record
*and* partition table from physical drives. Here's the updated code...

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' BOOTSEX.BAS   reads the hard drive boot sector into memory.
'
'   Author:     Christy Gemmell
'   Additions:  Martin Overton
'               David Milton
'   Date:       4/7/1995
'
'   $INCLUDE: 'VBDOS.BI'
'
    DECLARE SUB BootSex (Drive$, ParTable%, Done%)

    CONST FALSE = 0, TRUE = NOT FALSE

    DIM SHARED Regs AS RegTypeX
    DIM SHARED Sector AS STRING * 512
    DIM SHARED Part AS STRING * 512

    CLS : PRINT : Drive$ = "C:"         ' Read from drive C:
    BootSex Drive$, ParTable%, Done%    ' Read boot sector
    IF Done% THEN                       ' If successful...
       PRINT "Boot Sector for Drive "; Drive$
       PRINT "========================"
       PRINT "Media descriptor  = "; HEX$(ASC(MID$(Sector, 22, 8)))
       PRINT "OEM Identifier    = "; MID$(Sector, 4, 8)
       PRINT "Volume label      = "; MID$(Sector, 44, 11)
       PRINT "Serial number     = ";
       FOR I% = 43 TO 40 STEP -1
               PRINT RIGHT$("0" + HEX$(ASC(MID$(Sector, I%, 1))), 2);
               IF I% = 42 THEN PRINT "-";
       NEXT I%
       PRINT : PRINT "File system       = "; MID$(Sector, 55, 8)
       PRINT
       IF ParTable% THEN
              PRINT "Partition Table for Drive "; Drive$
              PRINT "============================"
              I% = 447: P% = 1
              DO
                     PRINT "Partition"; P%;
                     IF ASC(MID$(Part, I%, 1)) = 128 THEN
                            PRINT TAB(21); "ACTIVE PARTITION";
                     END IF
                     OS% = ASC(MID$(Part, I% + 4, 1))
                     PRINT TAB(41);
                     SELECT CASE OS%
                             CASE 0
                                      PRINT "Empty"
                             CASE 1
                                      PRINT "DOS 12-bit FAT"
                             CASE 4
                                      PRINT "DOS 16-bit FAT (up to 32MB)"
                             CASE 5
                                      PRINT "Extended partition"
                             CASE 6
                                      PRINT "16-bit FAT (over 32MB)"
                             CASE 7
                                      PRINT "OS/2 HPFS or Windows NTFS"
                             CASE ELSE
                                      PRINT
                     END SELECT
                     I% = I% + 16: P% = P% + 1
              LOOP UNTIL P% > 4
              PRINT
              Sig& = ASC(MID$(Part, I%, 1)) _
               + (256& * ASC(MID$(Part, I% + 1, 1)))
              IF Sig& = 43605 THEN
                     PRINT "Valid boot block"
              END IF
       END IF
       PRINT "-----------------------------------------------------------"
    END IF
END

'   Read the boot sector and partition table of a specified drive.
'
SUB BootSex (Drive$, ParTable%, Done%)
    LSET Sector = STRING$(512, 0)       ' Fill sector buffer with zeroes
    Disk% = ASC(UCASE$(Drive$)) - 65    ' Get drive number
    Head% = 0                           ' Floppies use head zero
    IF Disk% > 1 THEN                   ' Adjust
       Disk% = (Disk% + 128) - 2        '   for hard
       Head% = 1                        '     disk
    END IF                              '       drives
    Regs.cx = &H1                       ' Get sector 1 of track zero
    Regs.dx = (Head% * 256) + Disk%     '   of selected drive
    Regs.ax = &H201                     ' Read one full sector
    Regs.bx = VARPTR(Sector)            ' Offset of read buffer
    Regs.es = VARSEG(Sector)            ' Segment of read buffer
    INTERRUPTX &H13, Regs, Regs         ' Read sector into memory
    IF Regs.flags AND 1 THEN            ' Test carry flag for error
       Done% = FALSE                    ' If set report an error
    ELSE                                ' Otherwise
       IF Disk% > 1 THEN                ' Hard drive
              LSET Part = STRING$(512, 0)   ' Fill partition buffer with zeroes
              Head% = 0                     ' Partition table is under head zero
              Regs.cx = &H1                 ' Get sector 1 of track zero
              Regs.dx = (Head% * 256) + Disk% ' of selected drive
              Regs.ax = &H201               ' Read one full sector
(Continued to next message)
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 * 1st 2.00o #323 * Someday my ship will come in... but I'll be at the airport.