Kris Buelens wrote:
COPYFILE (PACK is very simple, I never looked in the actual details
but it replaces multiple occurances of the same character, inexpensive
but not lots of gains. TERSE is much like ZIP and VMARC. The FCOPY
tool on the download lib has a PACK option too, but that works like
TERSE, not like COPYFILE.
A reason why COPYFILE (PACK is used to transfer files from VM into the
PC world, is that a safe binary download/upload is only possible for
files with a FIXED recordlength. COPYFILE (PACK makes every file
F1024 (TERSE too and VMARC F80; FCOPY creates a RECFM V file)
From the 1985 internal announcement of TERSE:
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TERSE is a program which compresses data. It is based on a new algorithm
developed by Victor Miller and Mark Wegman of IBM Research at Yorktown
("Variations on a theme by Ziv and Lempel" - Research RC 10630).
The compression algorithm is adaptive, and does quite well on a variety
of file types, usually much better than HUFF or HUFFMOVE.
-------------------
I could likely dig up a copy of RC10630 if anybody is really that
interested.
Ray
