1.Bootstrap program …

In computing, bootstrapping (from an old expression "to pull oneself up by one's bootstraps") is a technique by which a simple computer program activates a more complicated system of programs. In the start up process of a computer system, a small program such as BIOS, initializes and tests that hardware, peripherals and external memory devices are connected, then loads a program from one of them and passes control to it, thus allowing loading of larger programs, such as an operating system.
A different use of the term bootstrapping is to use a compiler to compile itself, by first writing a small part of a compiler of a new programming language in an existing language to compile more programs of the new compiler written in the new language. This solves the "chicken and egg" causality dilemma.

2. Difference of interrupt and trap and their use . . .

Trap is actually a software generated interrupt caused either by an error (for example division by zero, invalid memory access etc.), or by an specific request by an operating system service generated by a user program. Trap is sometimes called Exception. The hardware or software can generate these interrupts. When the interrupt or trap occurs, the hardware therefore, transfer control to the operating system which first preserves the current state of the system by saving the current CPU registers contents and program counter's value. after this, the focus shifts to the determination of which type of interrupt has occured. For each type of interrupt, separate segmants of code in the operating system determine what action should be taken and thus the system keeps on functioning by executing coputational instruction, I/O instruction,storage instruction etc.
a trap is a type of PDU used to report an alert or other asynchronous event about a managed subsystem. While interrupt is an asynchronous signal indicating the need for attention or a synchronous event in software indicating the need for a change in execution.

3.Monitor mode

Monitor mode, or RFMON (Radio Frequency Monitor) mode, allows a computer with a wireless network interface card (NIC) to monitor all traffic received from the wireless network. Unlike promiscuous mode, which is also used for packet sniffing, monitor mode allows packets to be captured without having to associate with an access point or ad-hoc network first. Monitor mode only applies to wireless networks, while promiscuous mode can be used on both wired and wireless networks. Monitor mode is one of the six modes that 802.11 wireless cards can operate in: Master (acting as an access point), Managed (client, also known as station), Ad-hoc, Mesh, Repeater, and Monitor mode.

4. User Mode

Every process started by Windows (with the exception of the System "process") runs in user mode. In this mode, programs cannot modify paging directly and so have no way of accessing other programs' memory except through API functions. Programs in user mode also cannot interfere with interrupts and context switching.

5. Device status table

Is there a way to get any third-party devices that are regularly sending SNMP traps to CIM7 to show up in the Device Status field relating to the trap severity? I am getting plenty of major error messages from one of my switches, but the device is still showing as normal. The status for systems on IM7 is determined by polling that system, not by events from it. For ProLiant systems this works well because we can get detailed status from them. For devices like switches, all we have is that it responded, so for that system the status will always be either green (its up) or red (its down.)

6. Direct memory access (DMA)

Direct memory access is system that can control the memory system without using the CPU. On a specified stimulus, the module will move data from one memory location or region to another memory location or region. While it is limited in its flexibility, there are many situations where automated memory access is much faster than using the CPU to manage the transfers. Systems like the ADC, DAC and PWM capturing all require frequent and regular movements of memory out of their respective systems. The DMA can be configured to handle moving the collected data out of the peripheral module and into more useful memory locations (like arrays). Only memory can be accessed this way, but most peripheral systems, data registers, and control registers are accessed as if they were memory. The DMA is intended to be used in low power mode because it uses the same memory bus as the CPU and only one or the other can use the memory at the same time.
The DMA system is organized into three largely independent parts. Though the three compete for the same memory bus, they have can be configured for independent triggers and memory regions.

7. Difference of RAM and DRAM

These terms all refer to different types of computer memory, or RAM - Random Access Memory. The "random" part means that any area of the memory can be communicated with while; DRAM is a computer's main memory that holds onto information for the mictorprocessor. The "D" stands for dynamic, meaning the RAM needs to have the information its holding continuously renewed or "refreshed".



8. Main memory

Refers to physical memory that is internal to the computer. The word main is used to distinguish it from external mass storage devices such as disk drives. Another term for main memory is RAM.
The computer can manipulate only data that is in main memory. Therefore, every program you execute and every file you access must be copied from a storage device into main memory. The amount of main memory on a computer is crucial because it determines how many programs can be executed at one time and how much data can be readily available to a program.


9. Storage Structure


One of the first decisions in designing a server is what persistent storage structures to use. This section discusses how we organized storage structures for the grid example. There are numerous ways to organized storage. The primary decision is where to store the information about each item on the grid. We first discuss the implemented design and then present a couple alternatives.


> Main memory- Refers to physical memory that is internal to the computer. The word main is used to distinguish it from external mass storage devices such as disk drives. Another term for main memory is RAM.
The computer can manipulate only data that is in main memory. Therefore, every program you execute and every file you access must be copied from a storage device into main memory. The amount of main memory on a computer is crucial because it determines how many programs can be executed at one time and how much data can be readily available to a program.
Because computers often have too little main memory to hold all the data they need, computer engineers invented a technique called swapping, in which portions of data are copied into main memory as they are needed. Swapping occurs when there is no room in memory for needed data. When one portion of data is copied into memory, an equal-sized portion is copied (swapped) out to make room.
Now, most PCs come with a minimum of 32 megabytes of main memory. You can usually increase the amount of memory by inserting extra memory in the form of chips.


>Magnetic Disk- magnetic disk - (computer science) a memory device consisting of a flat disk covered with a magnetic coating on which information is stored

>Moving head disk mechanism






















10. Storage Hierarchy
• Storage systems organized in hierarchy.
– Speed
– Cost
– Volatility

>Caching – copying information into faster storage system; main memory can be viewed as a cache for secondary storage. >Coherence and Consistency-Transactional Coherence and Consistency (TCC) offers a way to simplify parallel programming by executing all code in transactions. In TCC systems, transactions serve as the fundamental unit of parallel work, communication and coherence. As each transaction completes, it writes all of its newly produced state to shared memory atomically, while restarting other processors that have speculatively read from modified data. With this mechanism, a TCC-based system automatically handles data synchronization correctly, without programmer intervention. To gain the benefits of TCC, programs must be decomposed into transactions. Decomposing a program into transactions is largely a matter of performance tuning rather than correctness, and that a few basic transaction programming optimization techniques are sufficient to obtain good performance over a wide range of applications with little programmer effort.