Sample Problems - IBM 709 General Information Manual

flag, examines the location specified by the address
(2054) and uses the address part of that location
(1500) to obtain an effective address. The subtraction
is then executed as if its address part had contained
1500 instead of 2054. Thus, the contents of location
1500 are subtracted from the contents of the accumu-
lator register.
The indirect addressing feature may be combined
with indexing to obtain even greater flexibility in op-
eration. Using the same example and adding an
index register tag, the operation would be as shown
in Figure 37.
location 2000
I I
3750
I
21 35
index reg i ster 1
[OO5fJ
Figure 37. Indirect Addressing and Indexing Format
The contents of index register 1 are subtracted
from the address portion of the subtract instruction
giving an effective address of 2000. Location 2000 is
then examined and its address portion (3750) be-
comes a second effective address. Thus the contents
of location 3750 instead of 2054 are subtracted from
the contents of the accumulator.
Sample Problems
The following figures show a few examples of some
of the problems that computers are solving today. Al-
though the examples shown are in scientific fields, the
computers are adaptable to business applications.
They are used for payroll, material inventory, control
of crude oil processing, and many other business ap-
plications where efficient operation depends upon
prompt, high-speed results.
The first application shown is in the field of scien-
tific research (Figure 38) .
Scatterer
I
Scatterer II
-" -----.
Figure 38. Neutron Scattering
20 IBM 709-7090
I
~
System Used
~709system
rfl
~7090
system
Time Taken
75 seconds
15 seconds
Figure 39. Time Comparisons. Neutron Scattering Problem
Neutron Scattering
Given:
l.
A spherically symmetric system consisting of two
scattering materials.
2. An initial neutron distribution in space and
energy.
3. Scattering laws for the materials and dimensions
for the system.
Find:
I. The neutron leakage rate from the system,
caused by scattering.
2. The asymptotic neutron distribution in space
and energy.
The initial collision distributions are combined ac-
cording to the scattering laws and are inserted into
matrix equations. These are multiplied by the mat-
rices and a new set of distributions is obtained. The
procedure is repeated on an iterative basis until the
asymptotic or limiting phase is reached.
Time comparisons for the solving of 25 of these
iterations appear in Figure 39 and are approximate.
Flight Trajectory
The second application is in the field of national de-
fense (Figure 40). The path of an object which is
launched from some arbitrary point is calculated. Its
trajectory is determined by its flight characteristics,
Initial
--l
Velocity
I
Components
j
I
Initial
j-
Initial
AI
Figure 40. Flight Trajectory
Ground