' DDT - Deep Disk Tester Rev.1.0
'
' Program design, development and programming by Richard Karsmakers
' Idea by Mr. I-forgot-his-name (in Veldhoven), but not mine anyway...
' Sunday, July 19th 1987
'
Alert 1,"Please insert disk|to be tested|in Drive A",1,"OK",Dummy%
'
' Read bootsector of disk to analyse the number of sides, tracks, sectors
'
Boot$=Space$(512)                                       !For bootsector
Check$=Space$(512)                                     !For check-sector
Dim B%(512)                                            !Wrong byte arrays
A%=Xbios(8,L:Varptr(Boot$),L:0,W:0,W:1,W:0,W:0,W:1)     !Read bootsector
If A%<>0                                                !Error occured?
  Alert 1,"An error occured!|Test aborted!",1,"Oh",Dummy%
  Edit
Endif
'
Sec%=Asc(Mid$(Boot$,20,1))+256*(Asc(Mid$(Boot$,21,1)))  !Sectors on disk
Spt%=Asc(Mid$(Boot$,25,1))+256*(Asc(Mid$(Boot$,26,1)))  !Sectors per track
Sid%=Asc(Mid$(Boot$,27,1))+256*(Asc(Mid$(Boot$,28,1)))  !Sides
Tps%=(Sec%/Spt%)/Sid%                                   !Tracks per side
'
Cls
Print "The disk has the following characteristics:"
Print "Total number of sectors  : ";Sec%
Print "Sectors per track        : ";Spt%
Print "Number of sides          : ";Sid%
Print "Nunber of tracks per side: ";Tps%
'
' The actual reading/checking takes place here
'
For S%=0 To Sid%-1                                      !Sides
  For T%=0 To Tps%-1                                    !Tracks per side
    For C%=1 To Spt%                                    !Sectors per track
      Print "Testing side: ";S%;", track: ";T%;", sector: ";C%
      @Check
    Next C%
  Next T%
Next S%
'
' The check routine
'
Procedure Check
  ' Read in sector
  A%=Xbios(8,L:Varptr(Check$),L:0,W:0,W:C%,W:T%,W:S%,W:1)
  If A%<>0
    Print "Read error on side: ";S%;", track: ";T%;", sector: ";C%
    Goto Label1
  Endif
  ' Buffer contents
  Buffer$=Check$
  ' Invert bits
  For X%=1 To Len(Check$)
    Mid$(Check$,X%,1)=Chr$(Asc(Mid$(Check$,X%,1)) Xor 255)
  Next X%
  ' Write sector back
  A%=Xbios(9,L:Varptr(Check$),L:0,W:0,W:C%,W:T%,W:S%,W:1)
  If A%<>0
    Print "Write error on side: ";S%;", track: ";T%;", sector: ";C%
    Goto Label1
  Endif
  ' Read it again
  A%=Xbios(8,L:Varptr(Check$),L:0,W:0,W:C%,W:T%,W:S%,W:1)
  If A%<>0
    Print "Read error on side: ";S%;", track: ";T%;", sector: ";C%
    Goto Label1
  Endif
  ' Invert bits
  For X%=1 To Len(Check$)
    Mid$(Check$,X%,1)=Chr$(Asc(Mid$(Check$,X%,1)) Xor 255)
  Next X%
  ' Check if buffer$ is still equal to the sector
  P%=0
  Arrayfill B%(),0
  For X%=1 To Len(Check$)
    If Mid$(Check$,X%,1)<>Mid$(Buffer$,X%,1)
      B%(P%)=X%
      Inc P%
    Endif
  Next X%
  ' Faulty bits?
  If P%>0
    Print "Byte faulty on side: ";S%;", track: ";T%;", sector: ";C%
    For X%=0 To P%
      Print "Faulty byte #";P%+1;": ";B%(P%)
    Next X%
    Goto Label1
  Endif
  ' Write sector back
  A%=Xbios(9,L:Varptr(Buffer$),L:0,W:0,W:C%,W:T%,W:S%,W:1)
  If A%<>0
    Print "Write error on side: ";S%;", track: ";T%;", sector: ";C%
  Endif
  Label1:
Return