Computer program for compressing program source decks and other data coded in Hollerith format is described. Compression of card image record by substitution of special code characters is discussed. Program is written for IBM 360/75/95 Release 19 computer

Merrill, E. O.

English

NASA Technical Reports Server

October 1972	 B72-10619 
NASA TECH BRIEF 
Goddard Space Flight Center 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Source Deck Compression and Update Program (CAPS) 
The problem: 
Continuous expansion of the volume of data main-
tained on punched cards, magnetic tape, and disk 
requires increasingly compact and efficient methods of 
storing, updating, and retrieving. 
The solution: 
A program, CAPS, which compresses program source 
decks or other data coded in Hollerith format. 
How it's done: 
A card image record is compressed by the substitution 
of special EBCDIC characters for each group of two or 
more sequential blanks occurring in the data. The 
hexadecimal numbers 02 through 3E are used to 
represent groups of from two blanks up to and in-
cluding 62 blanks, respectively. If there are 63 blanks 
in a group, no substitution is made for the 63rd blank. 
If there are more than 63 blanks, the 63rd and following 
blanks are compressed as a separate group. Since input 
data may be expected to include any of the special 
characters 00 through 3E, the hexadecimal character 00 
is used as a flag when such characters do occur. Other 
characters are used to identify the beginning and end of 
a deck and to indicate whether a deck is in compressed
or uncompressed form. Assignment of sequence numbers 
and provision for updating of compressed decks permit 
maintenance of a CAPS library of program decks (or data 
files) on a sequential data set. 
Notes: 
I. The user is to supply system subroutine LAND 
(Logical AND function). The compilation will give 
an unresolved external reference error if this function 
is not used. 
2. This program is written in FORTRAN IV (959o) and 
ASSEMBLER (5%) languages for the IBM-360/75/95 
Release 19 computer. 
3. Inquiries concerning this program should be directed 
to:
COSMIC 
112 Barrow Hall 
University of Georgia 
Athens, Georgia 30601 
Reference: GSC-1 1545
Source: Earl 0. Merrill of

Programming Methods, Inc.
under contract to

Goddard Space Flight Center 
(GSC-1 1545) 
Category 09 
This document was prepared under the Sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
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Source deck compression and update program (CAPS)

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