what is the difference between real mode and protected mode memory addressing?
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Answer: The main difference is the mode the cpu is in. In protected mode the OS can use features like paging and virtual memory. Also real mode code is never in 32 bits whereas protected mode code can be 16 bits or 32 bits.
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A 32-bit system can access 232 memory addresses, i.e 4 GB of RAM or physical memory. A 64-bit system can access 264 memory addresses, i.e actually 18-Quintillion bytes of RAM. ... A 64-bit register can theoretically reference 18,446,744,073,709,551,616 bytes, or 17,179,869,184 GB (16 exabytes) of memory.
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There is one major difference between a read-only memory (ROM) and a random-access memory (RAM) chip: ROM can hold data without power and RAM cannot. Essentially, ROM is meant for permanent storage, and RAM is for temporary storage.
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The data memory type may be used to declare variables only. ... This memory is directly accessed using 8-bit addresses and is the on-chip RAM of the 8051. It has the shortest (fastest) access time but the amount of data is limited in size (to 128 bytes or less). Variables declared data are located in the DATA memory class.
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The differences are pretty much just the same as between any other program's 32-bit and 64-bit versions. ... 32-bit has a maximum user-mode memory address space of 2GB, while 64-bit has an effectively-unlimited maximum memory (2^63 bytes, far more than the physical memory of any existent computer).
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KEY DIFFERENCE Primary memory data is directly accessed by the processing unit whereas Secondary memory data cannot be accessed directly by the processor. Primary memory is costlier than secondary memory whereas Secondary memory is cheaper compared to primary memory.
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The 1-byte instruction has an opcode alone. The 2 bytes instruction has an opcode followed by an eight-bit address or data. ... While storing the 3 bytes instruction in memory, the sequence of storage is, opcode first followed by low byte of address or data and then high byte of address or data.
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KEY DIFFERENCE Primary memory is also called internal memory whereas Secondary memory is also known as a Backup memory or Auxiliary memory. Primary memory can be accessed by the data bus whereas Secondary memory is accessed by I/O channels.
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['Protected and supervisor mode.', 'Allows disk access and file systems Device drivers Networking Security.', 'Program Execution.', 'Memory management Virtual Memory Multitasking.', 'Handling I/O operations.', 'Manipulation of the file system.']
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There is a Current Processor Status Register (CPSR) which is the same across all processor modes. Then there is the Saved Processor Status Register (SPSR) which is specific to each mode, with the exception of User mode and System mode (the two least privileged modes) which do not have a SPSR.
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FIFO does not have address input, it takes care of that on its own. It has counters(gray usually) for address generation. memory has the address input.
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['"Primary memory" is the memory which is much quicker and has higher access speed in comparison to the secondary memory. ... ', 'After cache memory, the primary memory has the highest access speed of all other types of memory devices.']
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Main memory or real memory is the memory that is physically present. It is the memory which all the processing units of a computer have direct access to. ... Virtual memory is a concept where you can run those program whose size is more than your RAM size..
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malloc is not a system call. It is implemented in libc and uses brk()/sbrk() and mmap() system call. Refer to Advanced Memory Allocation for more details.
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DESCRIPTION top. ioperm() sets the port access permission bits for the calling thread for num bits starting from port address from. If turn_on is nonzero, then permission for the specified bits is enabled; otherwise it is disabled. If turn_on is nonzero, the calling thread must be privileged (CAP_SYS_RAWIO).
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Answer: When the first m/c code of an instruction is fetched and decoded in the instruction register, the microprocessor recognizes the number of bytes required to fetch the entire instruction. For example MVI A, Data, the second byte is always considered as data.
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Primary memory holds only those data and instructions on which the computer is currently working. It has a limited capacity and data is lost when power is switched off. It is generally made up of semiconductor device. These memories are not as fast as registers.