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BRL 1961, FADAC, start page 0254
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FADAC
Field Artillery Digital Automatic Computer
MANUFACTURER
Autonetics Division
North American Aviation, Incorporated
Photo
Photo by U. S. Army
APPLICATIONS
FADAC -Field Artillery Digital Automatic Computer is a
rugged, general purpose, portable computer developed under
the sponsorship of Frankford Arsenal. FADAC design is based
on the existing requirements for solving gunnery problems of
tube artillery, free rockets, and missiles. Extreme
versatility also enables solution of field artillery support
computations related to surveying, counter battery, fire
planning, flash and sound ranging, reduction of
meteorological data, and master control and programming for
automatic checkout of missile systems.
Mechanization of FADAC is based on solution of the
differential equations of projectile motion from firing to
impact. Necessary input data such as target location, powder
temperature, gun location, meteorological data (inserted
manually or by tape reader) are entered by means of a
simplified keyboard. FADAC training time for experienced
fire control personnel is extremely short. When all data are
entered, depression of a button initiates computation; gun orders
comprising deflection, quadrant elevation, fuze time, and
charge are displayed in decimal form.
A high-speed automatic logic tester and a component tester
are also available with FADAC; these are in addition to the
self-checking features within the computer.
PROGRAMMING AND NUMERICAL SYSTEM
Internal number system Binary
Binary digits/word 35
Binary digits/instruction 35
Instructions/word 1
Arithmetic system Fixed point
Instruction type 1 plus 1
Address of operand and next instruction
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BRL 1961, FADAC, start page 0255
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Photo
Control Panel of the FADAC ComputerPhoto by U. S. Army
The matrix switches (A) allow the operator to enter fire
control parameters or select prestored parameters. Depression of
one button in the vertical row and one button in the
horizontal row selects one of sixty-four locations and identifies one
particular problem parameter. The manual keyboard (B) allows
the operator to enter problem information for different type
fire missions which has not been prestored in the memory.
The mechanical tape reader (C) is used for entering the
meteorological data which are contained on a punched tape.
Final problem solutions are displayed on the 16 Nixie tubes(D).
Word format
+--------+------+--------+--------------------------+
| 1 | 1 | 2 | 31 |
+--------+------+--------+--------------------------+
| Parity | Sign | Spacer | Numerical Absolute Value |
+--------+------+--------+--------------------------+
Five 1-word registers for arithmetic and control
One 2-word register for output information storag System
is straight binary for internal operations
with automatic conversions to other codes for input-
output. Twos complement notation for negative num-
bers is used.
ARITHMETIC UNIT
Add time 7.8 Microseconds
Execution time for each instruction is 7.8 micro-
seconds. High speed (2-bits at a time) multiplica-
tion, division and shifts.
Arithmetic mode Parallel by function
Serial by bit
Timing Synchronous
Pulse repetition rate 448,000 pulses/sec
Operation Sequential
STORAGE
Media Words
Magnetic Disc (Main)4,096
Magnetic Disc (Hi-Speed) 32
32 channels of 128 words each, of which 24 channels are
designated as permanent storage and 8 channels as working
storage.
The 32 words are two word high speed loops. Disc rotates
at 6,000 rev/min and its storage is nonvolatile.
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BRL 1961, FADAC, start page 0256
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INPUT
Media Speed
Keyboard Manual
Paper Tape Mechanical
Paper Tape 700 char/sec
Gunnery Off Console Manual
Another FADAC
Magnetic Tape
Other FIELData Equipment
Teletype
Five or eight channel paper tape, 5-level teletype or
FIELData code. Automatic conversion to machine language
provided. Maximum inputrate is 4,250 char sec.
OUTPUT
Media
Visual Display (Nixie)
Signal Level (Console)
Another FADAC
Battery Display
Printer
Magnetic Tape
FIELData Equipment
Teletype Equipment
System provides information in either 5-level teletype, 2-
wire teletype, or FIELData codes. Maximum output rate is
approximately 4,250 characters per second.
CIRCUIT ELEMENTS OF ENTIRE SYSTEM
Transistorized
CHECKING FEATURES
Parity check on FIELD at a information transfer. Verify
feature on input in program-full mode. Marginal test
provision for preventive maintenance. Voltage transient and
temperature warning indicators.
POWER, SPACE, WEIGHT, AND SITE PREPARATION
Power, computer 0.700 Kw
Three phase, 4-wire, 400 cycles/sec, 120208 volts.
Automatic power loss interlocks and phase reversing
features are provided.
Volume, computer 5 cu ft
Weight, computer 175 lbs
System operates from -25oF to 125oF (external ambient
at sea level). Capable of operating to -40oF with kit.
Automatic temperature protection is provided.
ADDITIONAL FEATURES AND REMARKS
Additional features include logic provision for expandable
memory; standardized etched boards utilized for reduction of
logistics problems; ruggedized for field use; system design
provides auxiliary equipment on an integrated basis for
computer memory loading, automatic computer testing, and
subassembly maintenance, and peripheral equipment for
additional operator control in program checkout.
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BRL 1961, FOSDIC, start page 0258
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FOSDIC
Film Optical Sensing Device for Input to Computers
MANUFACTURER
U. S. Department of Commerce
National Bureau of Standards
Photo
Photo by the Bureau of the Census
APPLICATIONS
System is utilized for the reading and conversion of
microfilm copies of Decennial Census Schedules (position
marked documents) to magnetic tape for computer input.
PROGRAMMING AND NUMERICAL SYSTEM
Internal number systemBinary coded decimal
Number bin cod dec dig/wordVariable
Number instructions decoded 45
Arithmetic system None
Instruction type Plugboard
FOSDIC converts coded marks on microfilmed documents to
information on magnetic tape in the following manner: (1) A
flying spot scanner tube is programmed to make several
calibration tests on each document measuring dark level,
light level, tilt, horizontal and vertical reduction
ratios. (2) The beam is then programmed using major and
minor jump instructions (coordinate increases or decreases)
to locate
1/4" black reference marks called "indexes". (3) From a
given index, program steps then positions the beam over each
possible marking position, measuring light output and
interpreting the result as either an "answer" or "no
answer". (4) The most dominant (darkest) of the answers is
held in memory until all positions for a given question have
been scanned. This answer (as coded by the program
plugboard) is written on magnetic tape. (5) Magnetic tape
format is UNIVAC compatible, 100 pulses/inch, 720 character
blocks in fixed format. The FOSDIC internal word and frame
lengths are variable, however, and many formats (number of
frames per block, number of digits per word) are possible
under program control.
STORAGE
Temporary fast storage by means of flip-flops.
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BRL 1961, FOSDIC, start page 0259
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Photo
Photo by the Bureau of the Census
INPUT
Medium Speed
Microfilm 2 - 4 frames/sec
Flying spot tube scanning
OUTPUT
Medium Speed
Magnetic tape 2,376 char/sec
Speed depends on amount of document information.
CIRCUIT ELEMENTS OF ENTIRE SYSTEM
Type Quantity
Tubes 1,200
Diodes 2,000
Transistors 3,000
FOSDIC consists of a Scan Unit constructed of vacuum
tubes, cathode ray tubes, photocells, magnetron beam-
switching tubes, and conventional pointto-point wiring;
and a Program Control Unit constructed of solid-state
components, transistors, diodes, etc., mounted on printed
circuit boards.
CHECKING FEATURES
Numerous scan, magnetic tape and program interlocks
sprocket and parity checking on magnetic tape output are
utilized.
POWER, SPACE, WEIGHT, AND SITE PREPARATION
Power, computer 5 Kw 5 KVA 1.0 pf
Volume, computer 3,000 cu ft
Area, computer 300 sq ft
Room size, computer20 x 20 x 10 ft
Floor loading, computer140 lbs/sq ft
Figures are for each system. Air conditioner is part
of integrated system.
Site preparation included alteration of area from
previously subdivided sections onto single enclosed area;
provision of air ducts and space air conditioning equipment;
alteration of lighting fixtures; provision of power consuits
and outlets; fire wall construction.
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BRL 1961, FOSDIC, start page 0260
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PRODUCTION RECORD
Number produced to date 5
Number in current operation 4
Number in current production 4
FOSDICs currently manufactured by Bureau of the
Census personnel for their own production needs.
COST, PRICE AND RENTAL RATES
Total cost for development and construction of 5
FOSDIC systems with 1 magnetic tape unit each
$633,000
PERSONNEL REQUIREMENTS
Three 8-Hour Shifts
Supervisors 3
Analysts
Programers } 3
Coders
Engineers 2
Technicians 10
In-Output Oper 12
Operation tends toward open shop.
Methods of training used
Training branch conducts formal classroom sessions for
programmers, operators (followed by on-the-job training
executive orientation, brush-up seminars. Classroom and on-
the-job training also conducted for engineers and
technicians.
Programmers are customer employees.
RELIABILITY, OPERATING EXPERIENCE,
AND TIME AVAILABILITY
Date this system passed Acceptance Test Sep 59-Mar 60 Time is
not available for rent to outside organizations. Each system
is operated an average of about 100 hours per week,
excluding scheduled maintenance.
ADDITIONAL FEATURES AND REMARKS
Prior to the invention of FOSDIC the bulk input medium
has generally been punch cards but a few figures showing
our experience in 1950 points out certain of their
limitations. At that time we used a force of nearly 2000
key punch operators at the peak of operations, and over 14
months was needed at a cost of almost six million dollars
just to record the enumerated population and housing data
on cards.
These facts led Census back to the Bureau of Standards
for additional study and review of the input problem. Out
of this interchange grew FOSDIC I. The name is an
abbreviation of Film Optical Sensing Device for Input to
Computers. Designed and built for Census by the Bureau of
Standards, it promised a breakthrough in the input problem
area.
The principle was based on field documents being
position coded (by checking the proper box, microfilming
the documents, and scanning the microfilm with an
electronic beam. The detected position codes are written
on the magnetic tape which is our computer input medium.
This early model FOSDIC served Census well. Several
special tasks were successfully processed through its use.
Its chief contribution, however, was in showing the way to
a more versatile, faster, less restrictive system.
Subsequently, Bureau of Standards and Census engineers
collaborated on a successor, FOSDIC III. In the meantime,
the Bureau of Standards had produced FOSDIC II which is
used by the Weather Bureau to do a high-speed search on
large punch card files which have been reduced to
microfilm.
FOSDIC III captured our imagination. It features a
completely programmable scan, permits tremendous
flexibility in schedule and questionnaire design, and has
such features as automatic calibration on each microfilm
frame measuring dark level, light level; compensation for
tilt or non-parallelism due to photography or printing;
compensation for size variation in the filming reduction
process; blank line elimination (conditional jumps over
partiallyfilled out documents); and dominant mark, an
ability to choose the darkest of several competing marks,
thus eliminating the problem of erasures. It is plugboard
programmed and has about 45 instructions and program loops.
Iterations are possible as with internally-stored program
computers. Documents are limited only to be 20" x 14" or
less, and their microfilm counterparts will be translated
to programmer-chosen codes on magnetic tape at about 100
frames or documents per minute. This works out to an
average character rate of about 19,000 24,000 characters
per minute. A tough rate for a key punch operator to match.
The 1960 Decennial Census
The equipment utilized 5 FOSDIC systems consists of:
4 Univac Scientific 1105 Computers with 18 tape units
each, 2 Univac I Computers with 10 tape units each, 2 600
lines per minute High-Speed Printers, equipped with Block
Buffers, 1 Card-to-Magnetic Tape Converter, and a host of
miscellaneous auxiliary equipment of a minor nature.
Adopted procedures for magnetic tape handling include
fire wall construction; metallic containers for magnetic
tape, fire fighting organization and training, control
system for defective and damaged tapes, and
standardization of tape reel lengths and markings.
INSTALLATIONS
Bureau of the Census
Washington, D. C.
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