     ATARI CHKDISK3 DOCUMENTATION
 
                                                   April 22, 1990
  

WARNING!! CHKDISK3 has not been through heavy testing and you use 
this program at your own risk. Proceed with caution. Back up your 
disks (especially hard disks) BEFORE you use CHKDISK3. This is a 
powerful tool which can fix damaged disks, but if it's misused, 
it can also damage good disks.

     The Atari CHKDISK3 program is a utility that analyzes a 
disk's file structure and does all of the necessary fixes. Before 
you use the program, you should have some basic knowledge about 
the disk and file structure.

     On the surface of each disk are invisible rings called 
tracks. The number of tracks on a hard drive depends on the size 
an type of the drive. A blank disk must be formatted in order to 
create these tracks. Each track is divided into many small 
fragments called sectors. Each track has sectors. Several sectors 
linked together are called a cluster. Directories and files are 
stored into data clusters. Some files may occupy one cluster and 
some may occupy more depending on the size of each file. To keep 
track of the status of each cluster, the disk contains a structure 
called a File Allocation Table (FAT). The FAT records which clusters 
are in use, which ones are free and which ones are physically 
damaged. A cluster which is logically allocated but has no file 
actually using it is called a "Lost Cluster". A cluster which is 
shared by two or more different files is called a "Doubly Used 
Cluster". A damaged cluster is called a "Bad Cluster".


                         USING CHKDISK3

You must specify the drive id and pathname for some options. Here 
are descriptions of all of the functions: 


FILE:


* Edit File

     Use this function to edit the clusters containing the 
     current file.

Att = Attributes ORing the following values:
     x00 normal file
     x01 read only
     x02 hidden from directory search
     x04 set to system, hidden
     x08 eleven-byte volume label
     x10 subdirectory
     x20 archive bit set

Clusters = the number of the starting cluster
* Analyse FAT

     This function scans through the disk and checks all of the 
clusters' allocation information. If it finds any Lost, Doubly 
Used, or Bad clusters, they are shown by using three different 
lines. The actual clusters number can be checked by clicking the 
arrows to scroll the window. Any Lost cluster can be recovered 
immediately by clicking the [Recover] button. Doubly Used 
clusters mean that the disk is logically damaged. Back up the 
disk (or partition) immediately and use HDX to reformat it.


* Show FAT map

     Show clusters' allocation map. On a colour monitor, different 
colour dots indicate non-contiguous clusters.


* Compress Disk

     This function compresses the current disk and frees up any 
Lost clusters. The Disk is compressed by removing empty clusters 
between allocated clusters. This function first analyzes the 
disk, then a second box comes up for the final confirmation. 
There is a percentage-completed chart to inform you about the 
progress of the compression. If the disk is badly fragmented, it 
may take a long time to do the compression.


     Warning! Do not attempt to change the disk while inside this 
    function. 


* Edit FAT table

     Allows you to edit the cluster links of the FAT table.


* Edit Disk Sectors

     Edit any sectors. The data is shown in hexdecimal form.

     F1 - Drive/Unit. Drive: a-z. Unit: 0-9
     F2 - Logical sector number to edit
     F3 - Absolute sector to edit
     F4 - Use the second FAT
     F5 - Edit root directory
     F6 - Go to previous sector
     F7 - Go to next sector
     F8 - Save edited sectors
     F9 - Hex or decimal input of sector number
     F10- Exit

MISC


* Force Media Change

     Force CHKDISK3 to read in the BPB again. This is useful 
after editing the FAT or sectors.


* Help

     Show the help menu

-- NOTE ---- NOTE ---- NOTE ---- NOTE ---- NOTE ---- NOTE ---- NOTE --

Use this program at your own risk and take it 'as it is'.

This program is not Public Domain (Atari owns the rights) but you may 
upload it into other Mailboxes and as long as you don't ask money for 
it and you don't edit/patch it.

Wilfred Kilwinger
Support Manager
Atari Benelux,
International Support Center

