EmbLogic » iittashish447

Device driver

iittashish447 — Tue, 13 May 2014 10:06:12 +0000

In computing, a device driver (commonly referred to as simply a driver) is a computer program that operates or controls a particular type of device that is attached to a computer.^[1] A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details of the hardware being used.

A driver typically communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device. Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware-dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface.

Operating systems

Common features
Process management Interrupts Memory management File system Device drivers Networking (TCP/IP, UDP) Security (Process/Memory protection) I/O

Character Device Driver

iittashish447 — Mon, 12 May 2014 05:56:20 +0000

The Internal Representation of Device Numbers
Within the kernel, the dev_t type (defined in ) is used to hold device
numbers—both the major and minor parts. As of Version 2.6.0 of the kernel, dev_t is
a 32-bit quantity with 12 bits set aside for the major number and 20 for the minor
number. Your code should, of course, never make any assumptions about the inter-
nal organization of device numbers; it should, instead, make use of a set of macros
found in . To obtain the major or minor parts of a dev_t, use:
MAJOR(dev_t dev);
MINOR(dev_t dev);
If, instead, you have the major and minor numbers and need to turn them into a dev_t,
use:
MKDEV(int major, int minor);
Note that the 2.6 kernel can accommodate a vast number of devices, while previous
kernel versions were limited to 255 major and 255 minor numbers. One assumes

PIPE

iittashish447 — Tue, 25 Mar 2014 09:47:48 +0000

The primitive for creating a pipe is the `pipe’ function. This creates
both the reading and writing ends of the pipe. It is not very useful
for a single process to use a pipe to talk to itself. In typical use,
a process creates a pipe just before it forks one or more child
processes (*note Creating a Process::). The pipe is then used for
communication either between the parent or child processes, or between
two sibling processes.

The `pipe’ function is declared in the header file `unistd.h’.

what is BIT

iittashish447 — Mon, 03 Mar 2014 07:44:07 +0000

Bit is a smallest unit of information.For defineing a bit we use the Voltage,Bit recognization,flow of wave or signal.

Master arry

iittashish447 — Thu, 20 Feb 2014 16:54:03 +0000

I have created master array. But the main problem to create master array by pointer.
Let see how it is done.