Share; Organization; Programming System - IBM 709 General Information Manual

Share
Organization
The present Share organization was conceived when
three customers, involved in preparation for a 704
Data Processing System, began informal discussions
concerning their individual plans and problems. The
mutual respect of the participants for the program-
ming competence of each other was expressed; they
were willing to accept the ideas of others, even to the
extent of obsoleting methods already prepared within
their own installations. It was agreed that a full-scale
attempt should be made to bring Share into being.
The first meeting was held in 1955 with seventeen
members present.
One of the advantages of an organization of this
type is that each member is closely united with the
development of computer usage throughout the world.
A substantial portion of the major users of high-
speed digital computers is represented in the Share
membership. It has been found that critical evalua-
tion of each other's ideas usually produces a distilla-
tion of thoughts, superior to any individual opinions.
Members realize substantial savings in programming
and check-out of programs. The continual inter-
change of ideas among members has demonstrated that
a high degree of computing sophistication is rapidly
built up in a Share installation.
In its initial phase, Share was concerned primarily
with procedures and standards. Later, the prepara-
tion and distribution of programs was started. No
slacking of activity is anticipated since, as the most
essential programs are completed, emphasis shifts to
new areas of mathematical computation.
Programming System
The Share 709 system is used with the 7090 Data
Processing System as the main programming system. It
enables the programmers to write, check-out, and alter
their programs quickly and easily. The Share 709
System (sos) can be thought of as composed of four
distinct parts:
1. The Share compiler assembler translator
(SCAT).
2. The program testing and correcting system.
3. The input-output system.
4. The MockDonald control system.
44 IBM 709-7090
The
SCAT
portion of the sos consists of two parts,
the compiler and the modify-and-Ioad program.
The compiler performs about the same functions
for the 709 and 7090 systems that the Share assembly
program
(SAP)
performs for the 704 system. With a
few minor exceptions, a Share assembly language pro-
gram is acceptable as input for the compiler and re-
sults in a program listing and an absolute binary pro-
gram card deck. In addition to the results produced
by Share assembly program, the compiler can produce
a "squoze" card deck. This deck contains the sym-
bolic source program in encoded binary form. This
form may be converted to machine language and
loaded by the modify and load program almost as
rapidly as an ordinary binary load program loads an
absolute binary card deck. Two main reasons for the
intermediate squoze card deck phase are:
1. Modifications to the program can be made in
the original
SCAT
language and then added to the
squoze deck for loading by the modify-and-Ioad
program.
2. Enough of the original symbolic information can
be retained during the program execution to per-
mit the checking and correcting program to re-
turn printed output in the original symbolic
language. In most instances, these two features
make it unnecessary to "patch" a program in
machine language. Thus, nearly all cross-ref-
erencing between symbolic and binary may be
avoided.
Another powerful tool in the compiler is the idea
of "macro-operation." The compiler is built to recog-
nize a large fixed number of macro-operations. It also
accepts and temporarily retains definitions of macro-
operations given by the programmer. In either case, it
generates and inserts into the program the sequence
of machine words specified by anyone of these macro-
operations in a macro-instruction. Among the sys-
tem (fixed) macros are all of the pseudo-operations
making up the checking and correcting program, the
input-output, and the MockDonald control system
languages.
A significant feature of the
SCAT
system is that the
loading process is also an assembly process. The
squoze deck is not in a form that can be inserted into
the computer as is. It is the result of what corresponds
to the first pass of the 704 Share assembly program sys-
tem. With
SAP
a second pass is needed to decode the
assembled deck into absolute binary. In the
SCAT
sys-
tem, the second pass is a function of the modify-and-