In a polling-based network receives, the operating system keeps checking the status register after a fixed time interval to see whether a device needs hardware attention or not. CPU gradually checks the status of receive bit after a defined time interval of a clock and if the value of receive bit is true then data is moved from the RX register to the memory. In interrupt-based networks, whenever a device needs hardware processing then an interrupt is raised to inform the CPU for device attention. The data of the device is transferred to memory from the network card.
Polling is a protocol, not a hardware mechanism where the device gets attention by CPU. An interrupt is a hardware mechanism, not a protocol where the device gets attention by the interrupt handler. In polling, during receiving, parts of received data need to transfer to memory but in case of interrupts, whole data is transferred at once after receiving is done. An interrupt is a heavy operation as compared to pooling because hardware involves in it. For large amounts of data, Polling becomes an inefficient method. In polling, CPU gradually checks devices at regular intervals whereas the Interrupt handler can send interrupt at any time. Each device has its own Command ready bit which indicates whether the device requires servicing or not. In polling, CPU wastes numerous clock cycles by repetitively checking the command-ready little bit of each device. In Interrupt based network, the interrupt request line indicates whether the device requires servicing or not. In interrupt-based network, CPU cycles not wasted but CPU is disturbed only when device send interrupt signals.
Relative performance between programmed I/O and DMA:
For determining the relative performance between programmed I/O and DMA, important factors are:
1. Size of data
2. Frequency of operations
Answer:
Static web pages are sent as it is at web server without being processed additionally.
Dynamic web pages content may change, and server hosting dynamic web pages return content after processing trough a program.
Examples of dynamic and static web pages are below
Explanation:
<em><u>dynamic websites</u></em>
f o o t y r o o m (.co) It is a football website. Displays latest highlights and football stats. It is dynamic because it gives live match scores, as the scores change, content change as well.
a c c u w e a t h e r (.com) It shows weather information. It is dynamic because when requested, displays current weather information.
x e (.com) It is a currency website. Dynamic because it shows live exchange rates.
<em><u>static websites</u></em>
s c i p y - l e c t u r e s (.org) It is a website about scientific python environment. It is static because it gives same content whenever requested.
d o g a c a n d u . b l o g s p o t (.com) it is a blog. Static because the requested content doesn't change unless the blogger adds a new story.
z t a b l e (.net) It is a website about z-score values and includes z-tables. It is static because its displayed as it is.
Wave energy and wind power (also hydroelectric dams as well), they create energy without pollution but need a lot of maintenance and some people disagree with their aesthetic influence of the countryside as they are very industrial looking <span />
Answer
Crawler
Explanation
This is a program that go to various website to read their pages and content provided in order to form entries for a search engine index.All search engines have this program called spider or a bot. It acts as an automated script that browses through the internet to scan the web pages and find words contained in the pages and where the words are used.
