EUGENE F. URETZ, JOHN A. MCCLARY AND STEVE MORGAN 
Table 111.— Data Directory Entries for TilOS7 
1249 
NAME 
CONDITION 
DESCRIPTION 
UNITS 
SEQUENCE 
ODHIGH 
High optical Density 
1 
ODLOW 

Low Optical Density 
2 
DILUTE 
Dilution Factor 
3 
SGPT 
S 
Serunn Glutamic 
Pyruvic Transami 
Karmen 
4 
FILE stores reference information needed by 
various system processors to perform their job. 
It is a hash coded file, a filing method which al- 
lows reference information to be quickly ac- 
cessed. Currently this file contains records 
describing staff members, tests, devices, and cali- 
bration data. Animal records are to be added to 
the file soon. It is beyond the scope of this paper 
to describe in detail the structure and content of 
the REFERENCE FILE, but the general con- 
tent and use of the file should become clear as 
we describe computer action upon receipt of the 
various context codes. 
DATA DIRECTORY. This file is part of the 
remote FIS system. It contains detailed specifi- 
cation of each facility test. A test is simply a 
specific T & E facility job or application which 
generally results in the acquisition of specific 
data items. Each such job is assigned a unique 
test number. The DATA DIRECTORY de- 
scribes the number of entries in each test, the 
order of entries, the meaning of each entry and 
the units of each entry. Table III shows the ref- 
erence file entries for a typical test. As data for 
each test is acquired by the Sigma-3, it must 
correspond exactly with the specifications set 
down in the DATA DIRECTORY. This is ac- 
complished by generating appropriate displays 
for the terminal user. The method is illustrated 
in a later section of this paper. 
USER PROCESSORS. As previously indi- 
cated, a wide variety of computer processing is 
handled on the Sigma-3. Required computations 
may be simple arithmetic operations of a few 
numbers, as in computation of oxygen trans- 
port, or may be relatively lengthy and complex 
computations as in doing a Fourier analysis of 
a blood flow or pressure curve. In order for the 
system to be adequate from the user's point of 
view, response times at the terminals must be 
commensurate with the complexity of the proc- 
ess being performed. This means that proces- 
sors which perform little computation must not 
be delayed even though a lengthy analysis is in 
the process of being performed. Also, the num- 
ber of user processors is expected to be contin- 
ually increasing. In order to allow system 
growth without continually adding core mem- 
ory to the system, it is necessary that user proc- 
essors be resident in core only when being exe- 
cuted. 
These capabilities were obtained by adding 
three semi-resident processing areas, in addi- 
tion to a non-resident foreground area provided 
