Computer software has to be "loaded" into the computer's storage (also known as memory
and RAM).
Once the software is loaded, the computer is able to operate the software. Computers operate
by executing the computer program. This involves passing instructions from the application
software, through the system software, to the hardware which ultimately receives the instruction as
machine code. Each instruction causes the computer to carry out an operation -- moving data,
carrying out a computation, or altering the control flow of instructions.
Data movement is typically from one place in memory to another. Sometimes it involves
moving data between memory and registers which enable high-speed data access in the CPU.
Moving data, especially large amounts of it, can be costly. So, this is sometimes avoided by using
"pointers" to data instead. Computations include simple operations such as incrementing the value
of a variable data element. More complex computations may involve many operations and data
elements together.
Instructions may be performed sequentially, conditionally, or iteratively. Sequential
instructions are those operations that are performed one after another. Conditional instructions are
performed such that different sets of instructions execute depending on the value(s) of some data. In
some languages this is know as an "if" statement. Iterative instructions are perfomed repetitively
and may depend on some data value. This is sometimes called a "loop." Often, one instruction may
"call" another set of instructions that are defined in some other program or module. When more
than one computer processor is used, instructions may be executed simultaneously.
A simple example of the way software operates is what happens when a user selects an entry
such as "Copy" from a menu. In this case, a conditional instruction is executed to copy text from
data in a document to a clipboard data area. If a different menu entry such as "Paste" is chosen, the
software executes the instructions to copy the text in the clipboard data area to a place in the
document.
Depending on the application, even the example above could become complicated. The field
of software engineering endeavors to manage the complexity of how software operates. This is
especially true for software that operates in the context of a large or powerful computer system.
Kinds of software by operation: computer program as executable, source code or script,
configuration.
and RAM).
Once the software is loaded, the computer is able to operate the software. Computers operate
by executing the computer program. This involves passing instructions from the application
software, through the system software, to the hardware which ultimately receives the instruction as
machine code. Each instruction causes the computer to carry out an operation -- moving data,
carrying out a computation, or altering the control flow of instructions.
Data movement is typically from one place in memory to another. Sometimes it involves
moving data between memory and registers which enable high-speed data access in the CPU.
Moving data, especially large amounts of it, can be costly. So, this is sometimes avoided by using
"pointers" to data instead. Computations include simple operations such as incrementing the value
of a variable data element. More complex computations may involve many operations and data
elements together.
Instructions may be performed sequentially, conditionally, or iteratively. Sequential
instructions are those operations that are performed one after another. Conditional instructions are
performed such that different sets of instructions execute depending on the value(s) of some data. In
some languages this is know as an "if" statement. Iterative instructions are perfomed repetitively
and may depend on some data value. This is sometimes called a "loop." Often, one instruction may
"call" another set of instructions that are defined in some other program or module. When more
than one computer processor is used, instructions may be executed simultaneously.
A simple example of the way software operates is what happens when a user selects an entry
such as "Copy" from a menu. In this case, a conditional instruction is executed to copy text from
data in a document to a clipboard data area. If a different menu entry such as "Paste" is chosen, the
software executes the instructions to copy the text in the clipboard data area to a place in the
document.
Depending on the application, even the example above could become complicated. The field
of software engineering endeavors to manage the complexity of how software operates. This is
especially true for software that operates in the context of a large or powerful computer system.
Kinds of software by operation: computer program as executable, source code or script,
configuration.
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