Service manual

Appendix A Test Equipment
FileStore Service Manual 106
FServEdit
Select E‘ from FServMenu, this invokes FServEdit, the sector-by-sector disc structure editor
and displays the following menu:
Edit FileStore structures on drive
A Add directory entry K Compare bit maps V Validate disc
C List map chain L List directory X Remove directory entry
D Change drive M List bit map blocks Y Re-validate bit maps
E Edit sector Q Quit this program Z Change disc name
H Display help message R Read sector
I Show disc information T Print tree
Using the options from the above menu you can edit the structure of a disc sector-by-sector,
making any kind of modification to the structure of a disc.
WARNING
It cannot be emphasised too strongly that FServEdit is completely ‗insecure‘ in that it lets you
do anything to any sector, with no consistency checking unless you explicitly ask for it. It is
very easy to delete data from sectors, or alter directories so that they no longer refer to files,
Of course, without this flexibility it would be less useful than it is.
The main features of FileStore discs that FServEdit knows about are:
 Directories
 Map chains
 Sectors
 The cylinder allocation bitmaps
 The disc name.
A FileStore directory contains, along with the catalogue information about a file, the sector
number (called the System Internal Number (SIN)) of an object called a ‗map chain‘ which is
a list of sector numbers where the data for the file can be found. This also applies to
directories. To refer So a file, you refer to the SIN of its map chain.
Each disc has a boot sector (and a redundant copy of this). FServEdit can list the contents of
the boot sector: this contains the SIN of the root directory, $ (really, the SIN of the map chain
that refers it).
Directories can be listed (‗List directory‘ ‗L‘) and entries can be added to them (‗Add entry‘,
‗A‘) and removed (‗Remove entry‘, ‗X‘).
Map chains can be listed (‗List map chain, ‗C‘).
The contents of sectors can be edited: there is screen editor to allow the user to alter the
contents of any disc sector, using the command ‗Edit sector‘ (‗E‘) or ‗Read sector‘ (‗R‘).
The cylinder allocation bitmaps can be listed (‗List bitmap blocks‘, ‗M‘) and checked:
‗Validate disc (‗V‘) makes a new allocation bitmap (in an ordinary disc file), by following the
directory entries on disc, without reference to the bitmaps on the disc; then ‗Compare
bitmaps‘ ( K‘) can be used to compare the bitmaps on the disc with the contents of this file,
and ‗Revalidate bitmaps‘ (‗Y‘) to replace the bitmaps on the disc with the ones from the file,
in the case that they are different.
The name of the disc: ‗Change disc name‘ (‗Z‘) is equivalent to the FileStore command
FSNamedisc.