Glossary

 

Argument

Functions and routines are passed arguments to process.

Ascii

American Standard Code for Information Interchange. Each letter of the alphabet is represented by an 8 bit code. Ascii is most often used to store written characters.

Bit

A single bit of data which represents either 1 or 0 (on or off).

Bottom Half Handler

Handlers for work queued within the kernel.

Byte

8 bits of data,

C

A high level programming language. Most of the Linux kernel is written in C.

CPU

Central Processing Unit. The main engine of the computer, see also em Microprocessor and processor.

Data Structure

This is a set of data in memory comprised of fields,

Device Driver

The software controlling a particular device, for example the NCR 810 device driver controls the NCR 810 SCSI device.

DMA

Direct Memory Access.

ELF

(Executable and Linkable Format) object file format designed by the Unix System Laboratories is now firmly established as the most commonly used format in Linux.

EIDE

Extended IDE.

Function

A piece of software that performs an action. For example, returning the bigger of two numbers.

IDE

Integrated Disk Electronics.

IPC

Interprocess Communiction.

Interface

A standard way of calling routines and passing data structures. For example, the interface between two layers of code might be expressed in terms of routines that pass and return a particular data structure. Linux's VFS is a good example of an interface.

ISA

Industry Standard Architecture. This is standard, although now rather dated, data bus interface for system components such as floppy disk drivers.

Kernel Module

A dynamically loaded kernel function such as a filesystem or a device driver.

Kilobyte

A thousand bytes of data, often written as Kbyte,

Megabyte

A million bytes of data, often written as Mbyte,

Microprocessor

A very integrated CPU. Most modern CPUs are Microprocessors.

Module

A file containing CPU instructions in the form of either assembly language instructions or a high level language like C.

Page

Physical memory is divided up into equal sized pages.

Pointer

A location in memory which contains the address of another location in memory,

Processor

Short for Microprocessor, equivalent to CPU.

PCI

Peripheral Component Interconnect. A standard describing how the peripheral components of a computer system may be connected together.

Peripheral

An intelligent processor that does work on behalf of the system's CPU. For example, an IDE controller chip,

Program

A coherent set of CPU instructions that performs a task, such as printing ``hello world''.

Register

A location within a chip used to store information or instructions.

Routine

Similar to a function except that, strictly speaking, routines do not return values.

SCSI

Small Computer Systems Interface.

SMP

Symetric Multiprocessing.

Software

CPU instructions (both assembler and high level languages like C) and data. Mostly interchangable with Program.

System V

A variant of Unix produced in 1983 which included, amongst other things, System V IPC mechanisms.

Task Queue

A mechanism for defering work in the Linux kernel.