Message switching is a connectionless network switching technique where the entire message is routed from the source node to the destination node, one hop at a time. It was a precursor of packet switching.ProcessPacket switching treats each message as an individual unit. Before sending the message, the sender node adds the destination address to the message. It is then delivered entirely to the next intermediate switching node. The intermediate node stores the message in its entirety, checks for transmission errors, inspects the destination address and then delivers it to the next node. The process continues till the message reaches the ... Read More

The Linux kernel modules can be loaded or removed from the kernel as required. This can be done without recompiling the kernel or rebooting the system and it enhances the functionality of the system.Without the kernel modules, the operating system would have to include all the systems that provide all anticipated functionalities in the base kernel. This would lead to wastage of memory as most of those systems would not be used often. Also, the users would need to rebuild and reboot the base kernel every time they would require a new functionality.The kernel modules have a .ko extension and ... Read More

The standard Java API and virtual machine are mainly designed for desktop as well as server systems. They are not that compatible with mobile devices. Because of this, Google has created a different API and virtual machine for mobile devices. This is known as the Dalvik virtual machine.The Dalvik virtual machine is a key component of the Android runtime and is a part of JVM (Java Virtual Machine) developed specially for Android. The Dalvik virtual machine uses features that are quite important in Java such as memory management, multi-threading etc. The programs in Java are first converted into JVM and ... Read More

Disks are the mainly used mass storage devices. They provide the bulk of secondary storage in operating systems today.Disk StructureEach modern disk contains concentric tracks and each track is divided into multiple sectors. The disks are usually arranged as a one dimensional array of blocks, where blocks are the smallest storage unit.Blocks can also be called as sectors. For each surface of the disk, there is a read/write desk available. The same tracks on all the surfaces is known as a cylinder.Disk SchedulingThere are many disk scheduling algorithms that provide the total head movement for various requests to the disk. ... Read More

#include int main() {    char str[100],i;    int upper = 0, lower = 0, number = 0, special = 0,whitesp=0;    printf("enter string");    gets(str);    for (i = 0; i < str[i]!='\0'; i++) {       if (str[i] >= 'A' && str[i] = 'a' && str[i] = '0' && str[i]