Category : HD Utilities
Archive   : SCAV31.ZIP
Filename : SCAVENGE.DOC

title scavenge Copyright (c) T. Jennings 1983

*****************************************
* *
* SCAVENGE *
* *
* Mark bad blocks on MSDOS *
* as allocated in the FAT. *
* *
* T. Jennings 5 June 82 *
* created 15 Sept. 82 *
* Modified 14 December 1984 *
* by David Gwillim *
* *
* *
*****************************************

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SCAV2XX was modified by David Gwillim to dynamically allocate
memory to the variables BLKBUF and FATBUF when the program
is started - this drastically reduced the size of the .COM file
from 17K on disk to just over 1K, while still allowing the
checking of disks with block sizes up to 16K Bytes. Also
changed was the access to disk to determine its statistics
(Number of Blocks, Blocksize etc) this is now done AFTER the
pause command when the program is first started, permitting
the program to be run with a single floppy drive. Code was
also added to display the block size of the disk in bytes
as part of the statistics, plus some alert tones for various
parts of the program.

I also added a more graceful exit than via ^C or Cntrl-Break
as this would often leave you on the wrong drive if you aborted
mid way through the block check and also would not give you the
chance to update the FAT with any bad blocks found so far.

A logical improvement to the program would be to add to the
code so the program could report the names of the files which
contain any bad blocks found, so the user could handle those
files, or at least be aware that the data in them was corrupted.

This is a very useful program and can give you great peace of
mind if you own a hard disk and want to be sure that all is OK.
If anyone takes a crack at doing the improvements I mentioned
or finds and fixes any bugs, I would be delighted to hear of
them.

David Gwillim
1414 N. Catalina Street
Los Angeles CA 90027

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Reads all sectors in logical MSDOS blocks and marks the file allocation
tables such that the blocks are permanently allocated where CHKDSK will
not deallocate them.


This version works on any 2.xx MSDOS or PCDOS, on any media type, fixed
or removable.
| [At least through my PC-DOS v3.1 and my Seagate ST251]

One (major) limitation: it will not map out blocks that are already allocated
to a file; it will say "block used", but won't tell you which file it is in.

If SCAVENGE finds any bad blocks, it will ask you whether or not you want the
disk updated. You can safely run it just to see if the disk is OK.

v3.01
- Slightly tweaked
- Removed some small system functions, placing them inline.
- Separated extensive documentation (the above) from the .ASM source,
placing it in a separate SCAVENGE.DOC file.
- No functional changes.
David Kirschbaum
Toad Hall
[email protected]