

                                The Disk Doctor


         The Display

              To examine the contents of a file or a disk, you must
         first open on from the file menu. To open a disk, specify the
         drive by its id letter in the selector window - ie A, B etc -
         then click on the OK box. The drive is opened and the first
         (#0) sector is displayed. To move to other sectors, you
         select either the 'go to' command in the sector menu or use
         the scroll bar at the right of the window (clicking on the
         arrows moves the display one sector in that direction, on the
         shaded scroll bar moves it 10 sectors). Sectors on a disk
         are, of course, always contiguous.


              To open a file, you must select the file from the GEM
         file selector window. You can move the mouse to the file and
         double click on it. If you want to change drives or folders,
         move the mouse to the drive id line and use the backspace or
         the arrow keys to correct the line. Then move the mouse to
         the shaded bar and click on it; the new directory will
         appear. Now find the file you want and double click on it.


              When a file opens, it shows the first sector of that
         file. Files are not necessarily stored in contiguous sectors
         on a disk, as explained in the sections about the directory
         and the FAT. You can move to the next sector in a file by
         clicking on the down arrow of the scroll bar or to the
         previous sector by clicking on the up arrow.


              In both disk and file displays, the screen results are
         the same. The currently displayed sector number is listed
         across the top. If it is a disk you've opened, the number is
         absolute; ie the number is the same as the sector being read
         from the disk. If it is a file, it is relative; that is: the
         sector is the first, second, etc of the total in the file but
         not necessarily the same number as that sector from which it
         was read off the disk. All number begins with zero.


              The sector is a number of so many; on a single sided
         floppy there are 720; 1440 on a double sided. The number in a
         file varies but the total will appear at the right of the
         sector number. Each value displayed represents one byte on
         the disk in that sector.


              Across the top are the numbers 0 to 29. Add this column
         to the row listed down the left side to get the position of
         the byte you want to address; a byte at column 26 and row 150
         is at location 176. There are 512 bytes in a sector and all
         are displayed on the screen at once.





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                                The Disk Doctor


              There are two displays available: character and hex. In
         character display (the startup default), any values having
         ASCII equivalents are displayed as their characters (from
         space to ~; hex $20 to $7E). This allows you to read text,
         data, file names in the directory, etc. Non-ASCII equivalents
         retain their hexadecimal values but are greyed-out (green in
         medium resolution unless you've changed the colors with the
         control panel). In hex display, all bytes are seen as black;
         none are greyed out.


              To test the display, open one of the help files (with
         the .HLP extender) on the Disk Doctor disk and examine their
         contents. You can switch back and forth between character and
         hex displays by clicking on the selection in the sector menu
         or toggle by pressing control-V (^V). You can print the
         contents of the sector in the chosen display mode by
         selecting the print option in the sector menu.


              Other displays available will show you information in a
         more obvious format; the sector links for a file, number of
         bytes used, starting sectors and similar information. You can
         print any information by directing it to the printer when the
         query window pops up or any screen by pressing and holding
         the 'Alternate key' and pressing the 'Help' key.


              The display will be further discussed in the sections on
         editing and the various menus.




























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