FADAC

    Field Artillery Digital Automatic Computer
    
             MANUFACTURER
    Autonetics Division
    North American Aviation, Incorporated
    
    
           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
 

    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.
 
 
 
          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.