This directory contains three programs for use in retrieving
and reconstructing files from a disk that cannot be read by VMS because
of a clobbered index file (INDEXF.SYS) or for other reasons.  Our problems
were caused by a failed disk head writing spurious data in critical
areas, causing the index file (among others) to be clobbered.

	The lack of an index file makes a disk unmountable.  To do any
of the disk operations in any of these programs, the disk is MOUNTed/FOREIGN.
In all these programs, we read data from the bad disk on SIA1 and
write to a good disk on SIA0.  Both our disks are 300 MB in size.

	1.  Program RINDX prepares an index file (on SIA0) containing 
headers of the files on SIA1.  It does this by reading SIA1, block by
block, and looking for "that telltale pattern" in the first four bytes.  Also
the file number stored in the header must be non-zero to be a legal header.

	(The program does NOT deal with files requiring multiple headers.
Multiple headers are needed for files that have a very large number of
mapping pointers, overflowing the pointer area allocated in the first header 
block.  Again: NO PROGRAM IN THIS DIRECTORY HANDLES MULTIPLE HEADER
BLOCKS.)

	RINDX also produces a list of the file headers found, their names,
their file numbers, and the block numbers where the header was found.

	2.  Program FILES is used to retrieve files from SIA1 and rebuild them
on SIA0.  FILES is run interactively. You enter a file number, and FILES
retrieves it (block by block) and rebuilds it. When you enter a file number,
FILES prints out the name and size of the file to verify that this is indeed
the file you want.  You obtain the file number from the listing of file
numbers vs. file names produced by RINDX. 

	3.  Program FILEX is similar to FILES, except that instead of
entering a file number, you enter the block number of the file header.
FILEX does not use the index file built by RINDX.  The reason FILEX 
exists is that we deleted the index file to save space after we thought
all needed files were retrieved from the bad disk.  It turns out we needed
some additional files after the index file was gone.  But given the disk
BLOCK NUMBER of the file header, FILEX restores the file on SIA0 just as
FILES does given the file number.

	If you have any comments or questions about these programs, feel
free to call me.

	Ray Stone
	General Research Corp.
	PO Box 6770
	5383 Hollister Ave.
	Santa Barbara, Ca. 93111    

	805-964-7724 ext. 441