WHAT IS A COMPUTER?
                                by Duane Bristow
                             The Helping Hand BBS
                                (606) 387-4002

        A computer is a machine which contains an electrical 
        microprocessor.  It is capable of storing information coded into 
        the states of electrical switches.  It is capable of following a 
        set of electrically coded instructions to process stored 
        information by copying, moving, and performing arithmetic and 
        other operations on that information.  It is also capable of 
        making comparisons of two different sets of information and 
        branching to a different set of instructions based on the 
        results of that comparison. 

        Computers are not smart, but because they are electrical, they 
        are fast and accurate.  This sometimes gives the impression of 
        intelligence even though, in fact, the computer is only a non-
        thinking machine. 

        Physically a computer is a CPU, Central Processing Unit, 
        containing the ALU, Arithmetic Logic Unit (chip) which performs 
        the above operations and RAM, Random Access Memory, where 
        information is stored during processing.  The amount of RAM and 
        the speed and power of the ALU plus the speed of the bus 
        determines the power of the system.  The bus is simply the 
        electrical circuits which connect the various parts of the 
        computer.  It is the path over which stored data, information, 
        travels.  The power of the processing chip, ALU, is determined 
        by the number and kind of instructions it is capable of 
        executing and by its speed of operation.  A special type of 
        memory similiar to RAM is ROM memory.  ROM means Read Only 
        Memory and contains permanent operating instructions for the CPU 
        which are built into the computer when it is manufactured.  This 
        memory is just like RAM except that the CPU cannot change its 
        contents or write to this type of memory. 

        Usually the ALU and RAM chips are mounted on a printed circuit 
        board which also contains the bus connecting the CPU to other 
        parts of the computer such as the power supply and various 
        input/output devices, I/O devices.  This main printed circuit 
        board is called the motherboard and it may connect to other 
        PC boards called daughter boards which control various I/O 
        devices and add capabilities to the system.

        A typical computer box such as the one you are now using might 
        contain an Intel 80386 chip with 640 thousand bytes of RAM, 
        640K.  It might have a 32 bit bus, meaning the bus is capable of 
        transferring 32 units of information at once.  This box might 
        also contain a 200 watt power supply and various input/output 
        and storage devices such as floppy disk drives, hard disk 
        drives, monitor control board, keyboard connector, etc.

        Typically, microcomputers such as this one are based on one of 
        the following intel processor chips:
                8088
                80286
                80386SX
                80386DX
                80486
        An internal clock determines the speed of operation, number of 
        instruction cycles per unit of time, the system is capable of 
        performing.  Clock speeds range from 4.77 MHz.to 33 MHz. or 
        more. MHz. stands for Megahertz.  One MHz. means one million 
        cycles per second.

        This typical computer would usually have from 64K to 640K to 1 
        megabyte to 4 or more megabytes of RAM and would have either an 
        8, 16, or 32 bit bus. 

        The original IBM PC worked on an 8088 chip with 64K RAM and an 8 
        bit bus operating at 4.77 MHz.  This computer contains an 
        80386DX chip with 1 million bytes RAM, a 32 bit bus, and a 16 
        MHz. clock speed.  It operates 18 times as fast as the original 
        IBM PC.

        The set of instructions for a computer is called a program or 
        software.  This tells the computer how to manipulate data and 
        enables it to do useful applications.