1 
Operational Use of the AP-2 at ACIC 
I. INTRODUCTION 
1. Introduction 
The AP-2 Analytical Plotter was delivered to ACIC 6 July 62. Since 
that time, we have been busy testing this instrument and training 
people in techniques and concepts for its application in an operations 
environment. Our experience with the AP-2 is the subject of this paper 
and will cover the following areas of interest: 
a. Operation Tests 
b. Problems associated with operation of the AP-2 
c. Evaluation of the AP-2 compared to conventional instrumentation 
It is believed that the information to be presented will help place 
the AP-2 in proper perspective so that realistic estimates of its per 
formance and capability can be predicted. 
II. BACKGROUND 
2 » Functional Description of the AP-2 
Before getting deeply committed to the technical details, it is 
worthwhile to spend a few minutes discussing the AP-2 from an 
operator's point of view. 
Figure lisa picture of the AP-2. Mechanically, an operator has 
three modes of controlling the machine's operation: through the con 
sole; through the tape reader; and through the foot and hand wheels. 
Conceptually, the AP-2 computer is made up of two computers. 
(See Fig 2) The DDA computer continually operates at the rate of one 
complete cycle every 10 milliseconds. During each cycle, it receives 
quanitized bits of collected from each of the (X m , Y m , Z ) foot 
discs and hand wheels, transforms them and corrects for various 
systematic distortions, and outputs its corresponding movement (Ax, Ay) 
to each of the comparator tables and to the plotter table. During 
the various steps in the DDA computations, constants data is drawn 
from the General Purpose Computer (GPC) and new data stored back 
again as it is developed. Each DDA cycle is broken up into 8o words 
times and up to four digital computations can be performed during 
each word time. 
The GPC controls the constants input, modification and read out of 
the instrument. As seen in the figure, it is only through the GPC 
that the operator can control the response of the freely cycling DDA