Notes, summaries, assignments, exams, and problems for Computers

Common Features of IPC Light Mechanisms

These mechanisms are implemented as a unit and share common features, including:

• All mechanisms have a table whose entries describe their usage. Each table entry has a numerical key chosen by the user.
• Each mechanism has a 'get' call to create a new entry or retrieve an existing one. The parameters of this call include a key and a mask of flags. The kernel searches the table for an entry that matches the provided key.
• If the key is set to IPC_PRIVATE, the kernel occupies the first free entry. Subsequent calls will return this entry until it is released.
• If the IPC_CREAT flag is active in the mask, the kernel creates a new entry if there is no match for the provided key. If both IPC_CREAT and IPC_EXCL flags

Software Applications and Data Handling

Spreadsheet Applications

Leaf is a software application that allows mathematical operations, working with numerical data, making complex calculations with formulas and functions, and generating graphs. In this unit, we will use the spreadsheet applications Excel and Calc.

Spreadsheet Errors

Spreadsheet errors do not tell us whether we made an error in an entry or operation. In Calc, error messages are available as codes. In Excel, the error messages are:

• #####: The cell width cannot display content, or you have used a negative date or time.
• #VALUE!: You have used an incorrect argument type or operation.
• #NAME?: The text of the formula is not recognized.
• #REF!: The cell reference is invalid.
• #N/A: Not available