Introduction to information systems T. Cornford, M. Shaikh is1 060 2013

4.3.1 Memory management
The operating system allocates some memory (RAM) to programs that 
are to be run and may alter this allocation as they run. For example, the 
spreadsheet has to be allocated some memory in which to locate itself 
(its code) and the data it manipulates. As more data is typed into the 
spreadsheet, more memory may be needed.
4.3.2 Input–output management
The operating system will manage input and output devices to enable 
programs to obtain input (for example, from a keyboard) and to 
produce outputs (for example, on screens or printers). For example, the 
spreadsheet will need input from the keyboard. It will ask the operating 
system for some keyboard input and will wait until it gets it. When the 
user types on the keyboard, it is the operating system that directly reads 
the keystrokes and passes them on to the spreadsheet program. The 
operating system may detect some special keystrokes, which it chooses to 
interpret and act upon itself, rather than passing on to the spreadsheet. 

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Chapter 4: Contemporary trends in information and communication technologies
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For example, the ‘Caps Lock’ key tells the operating system to pass all 
characters to the spreadsheet as capital letters. 
4.3.3 Secondary storage management
Secondary storage management is done through a file system. The 
operating system allocates space on a disc to contain a file, and maintains 
a directory of file names and locations. This means that a file can be 
subsequently located and read. When the operating system is told to run 
the spreadsheet, it is, in effect, told to find a file of program code and load 
it into memory. Similarly, if when using the spreadsheet we decide to store 
the work that has been done, this results in a request to the operating 
system to find some free space on the disc, give it a designated file name 
and write the contents of our spreadsheet on to the disc.