TOPIC 1—COMPUTER FUNCTIONS AND TYPES The   computers   the   Navy   uses   vary   from mainframes to microcomputers. Regardless of the types of computers and their operational uses, their functions are basically the same. Depending on the type of computer and the operational use, the methods will vary. First, we discuss the functions of computers, the different ways computers handle data, and the methods they use to accomplish this. Then we discuss the functional operation of computers. COMPUTER  FUNCTIONS All computers must be able to gather, process, store, disseminate, and display data. Gather Data All computers, no matter what their size, must gather data before they can process the data. The operational program  will  dictate  how  the  data  is  gathered— manually, automatically, or a combination of both. Manually, an operator or technician will input the data to the computer. This can be done either directly or by a device external to the computer. The following are commonly used input devices: Keyboards Display  consoles Data terminals Computer maintenance panels Storage devices (magnetic tape units, disk drive units, and paper tape units) As an example, an operator at a console will input data via the console to the computer and the computer will process the data for storage, dissemination, or display depending  on  the  functions  of  the  operational  program. Data may be input from a console using pushbuttons, switches, toggles, or a combination of these. Automatically gathering data means the computer receives  data  from  another  system,  subsystem,  or equipment.  The  computer  monitors  for  external requests through a series of programmed requests and acknowledges.  The  computer  first  sees  the  gathered data  when  it  comes  through  the  input  section  of  the input/output section of the computer. Then depending on the operational program, the computer will either react immediately or store the data for future use. The following are examples of the sources from which computers gather the data automatically: Systems such as the fire control system Subsystems  such  as  the  combat  direction  system Data processing systems (another computer and conversion devices) Display systems via sensors (radar) Communication systems such as data links and local-area networks (LANs) Many computer systems are designed to gather data using a combination of both the manual and automatic methods. Process  Data Processing  data  is  the  main  function  and  the purpose of the computer. There are other systems, subsystems,  and  equipment  that  will  work  with  the computer  to  help  gather,  store,  disseminate,  and  display data;  but  processing  the  data  is  exclusively  the computer’s function. The heart of the computer—the place where the data is processed in a computer-is called the central processing unit (CPU). Figure 1-1 shows the basic configuration of a digital computer. After  the  data  is  processed,  it  can  be  stored, disseminated, or displayed. Store Data The  computer  can  store  data  either  internally  or externally.  Internally,  the  computer  uses  memory Figure  1-1.—A  basic  functional  composition  of  a  digital computer. 1-2