A special control unit is provided to allow transfer of a block of data directly between an external device and the main memory, without continuous intervention by the processor. This approach is called direct memory access, or DMA. DMA transfers are performed by a control circuit that is part of the I/O device interface. We
This portion consists of the page table entries that correspond to the most recently accessed pages. A small cache, usually called the Translation Lookaside Buffer (TLB) is incorporated into the MMU for this purpose. The operation of the TLB with respect to the page table in the main memory is essentially the same as the
The process of translating a virtual address into physical address is known as address translation. It can be done with the help of MMU. A simple method for translating virtual addresses into physical addresses is to assume that all programs and data are composed of fixed-length units called pages, each of which consists of a
Cache is small memory which is very fast in access , so when processor want to access the data it tries to find out in cache , if it is found then it is known as cache hit and in case of not found , it is known as cache miss. In most of
Why it is used ? Virtual memory is used to increase the apparent size of the physical memory. Data are addressed in a virtual address space that can be as large as the addressing capability of the processor. But at any given time, only the active portion of this space is mapped onto locations in
1.Requires less registers therefore it is easier to design where in Cisc it is more expensive to make compared to RISC 2. Risc :Faster than CISC , Cisc is slower chips when performing instructions where 3. Risc : Reduced Instruction Set Computer CISC : Complex Instruction Set Architecture 4 Pipelining can be implemented easily , where
Exceptions and interrupts are unexpected events that disrupt the normal flow of instruction execution, when it occurs following things happens move the current PC into another register, call the EPC record the reason for the exception in the Cause register automatically disable further interrupts or execptions from occuring, by left-shifting the Status register change control (jump) to a hardwired exception handler
Differences 1. The most obvious one : Initial blocks get executed at the beginning of the simulation, final block gets executed at the end of simulation 2. Final block has to be executed in zero time, which implies it can’t have any delay, wait, or non-blocking assignments. Initial block doesn’t have any such restrictions of
With inheritance we are able to force a subclass to offer the same properties like their superclasses. Consequently, objects of a subclass behave like objects of their superclasses. Sometimes it make sense to only describe the properties of a set of objects without knowing the actual behaviour beforehand Abstract classes are those which can be
A set of classes can be created that can be viewed as all being derived from a common base class. For example, a common base class of type BasePacket that sets out the structure of packets but is incomplete would never be instantiated. From this base class, however, a number of useful subclasses could be
