COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	CRUNCHING AND SPINDLING FILES
C00006 ENDMK
C⊗;
CRUNCHING AND SPINDLING FILES


	SPINDL and CRUNCH are two programs for reducing the amount
of disk space occupied by a user's files.  SPINDL combines several
files into one in such a way that the original files can be restored,
keeping their names accessible so the user can tell what he has, and
crunch uses Huffman coding toreduce the disk spae occupied by a
file.

	Since computer time is required to SPINDL, UNSPINDL, CRUNCH,
and UNCRUNCH, and programs that used files cannot use them in compressed
form, a file should be compacted only if it is not going to be used
for a while.  With the KA-10, our rule-of-thumb is that small files
should be SPINDLed if they are not going to be used for 10 days, and
a file should be CRUNCHed if it is not going to be used for 30 days.
If a file has not bee used for twice these times, then it should
be considered a %2prima facie%1 candidate for these procedures.
When the KL-10 is working the balance will shift further in the
direction of CRUNCHing and SPINDLing.

SPINDL

	The command for SPINDLing is

	SPINDL <FILE NAME> ← <LIST OF FILE NAMES>

If the left file name exists, it is assumed to be a SPINDL file
already, and the files referred to by the list are combined into
with it to make a larger SPINDL file.  If the file doesn't exist
it will be created.  If no extension is mentioned, the SPINDL
file will have the extension SPI.

A SPINDL file has a directory page that contains a list of the
files that have been SPINDLed to make it.

UNSPINDL

	Retrieving a file from a %2spindle%1 is called UNSPINdling,
and its syntax is

	UNSPIN <LIST OF FILE NAMES> ← <FILE NAME>

The files listed on the left will be extracted from the file named
on the left of the arrow.

CRUNCH

	CRUNCHing a file normally reduces it to 40% to 50% of its
length.  It is pointless to CRUNCH a file whose size is less than
1.7K, because the new file will take up 2304 words anyway.  Such
files should be SPINDLed.


CRUNCHing a file uses two auxiliary files.  One of these is a list
tree of %2left contexts%1, and the other is a Huffman code for each
character in each left context.  These tables can be created in
an optimal way for each file, but experiment has shown that standard
versions for different classes of files work well enough.  The
syntax to CRUNCH is