Dialog Edit FAT
The File Allocation Table dialog provides a visual and tabular view of how clusters are allocated within the active image.
It allows inspection and controlled editing of FAT entries, making it possible to identify allocation issues, trace file cluster chains, and correct certain types of filesystem inconsistencies.
- Menu: Edit → File Allocation Table
If multiple FAT copies exist, the active FAT is determined by the current FAT selection.
The dialog is divided into two main areas:
- A cluster map, which provides a visual overview of cluster usage
- A FAT entry table, which lists individual cluster entries in detail
Edits made in this dialog are staged and are not applied until Update is clicked.
The cluster map displays the allocation state of each cluster using color-coded blocks. Each block represents a single cluster.
This view allows quick identification of fragmentation, unused space, damaged areas, and unusual allocation patterns.
The cluster map uses color to convey allocation state and potential issues at a glance.
-
Blue — Allocated clusters
Indicates clusters that are part of a file’s allocation chain. -
White — Unallocated clusters
Indicates free space that is not currently assigned to any file. -
Red — Error conditions
Indicates clusters involved in allocation errors, such as:- Bad sectors
- Circular cluster chains
- Lost clusters
When hovering over an allocated cluster, all clusters associated with the same file are highlighted in green.
This makes it easy to visually trace a file’s cluster chain and identify fragmentation or unexpected allocation patterns.
Hovering the mouse over a cluster displays a tooltip containing:
- The cluster number
- The file associated with the cluster, if any
- Any allocation errors detected for that cluster
This allows quick inspection without switching views.
Opening the context menu on a cluster provides direct editing and navigation options.
Available actions include:
-
Set Free
Marks the cluster as unallocated. -
Set Bad
Marks the cluster as unusable. -
Set Last
Marks the cluster as an end-of-chain marker. -
Set Reserved
Marks the cluster as reserved. -
View in Hex Editor
Opens the selected cluster location in the hex editor.
Changes made using the cluster map are reflected immediately in the FAT entry table.
The FAT entry table lists clusters in numeric order and provides detailed information for each entry.
-
Cluster
The cluster number. -
Type
Describes how the cluster is used (for example, Free, Next, Last, Bad, or Reserved). -
Value
The raw FAT value associated with the cluster. -
Error
Displays detected allocation errors, such as cross-linked or circular chains. -
File
The file currently associated with the cluster, if known.
FAT entries can be edited directly from the table.
- The Value field may be edited inline to change the FAT entry for the selected cluster.
- Shortcut buttons above the table (Free, Bad, Last, Reserved) can be used to assign a value to the currently selected row without manual entry.
Both methods update the cluster map immediately.
Additional information related to the FAT is displayed below the cluster map:
-
Valid Clusters
Indicates the usable cluster number range for the image. -
Media Descriptor
Displays or allows selection of the FAT media descriptor value.
When multiple FAT copies exist and their contents do not match, an additional option appears at the bottom of the dialog:
- Synchronize FATs
When enabled, any changes made to the currently active FAT are automatically applied to the other FAT copy as well.
This provides a convenient way to keep FAT copies consistent while making repairs or adjustments.
- Applies all staged changes to the FAT
- Marks the image as modified
- Closes the dialog without applying changes
- The dialog operates on the active image
- Changes are staged until Update is clicked
- Editing FAT entries can affect file integrity and filesystem structure
- Allocation errors are surfaced elsewhere in the interface for visibility