Disabled by setting the i or f bit respectively in

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disabled by setting the ‘I’ or ‘F’ bit respectively in CPSR. Interrupt Service Routine (ISR) must save and restore conflict registers and SREG The exception processor can save and restore some register and CPSR. Other registers are banked which mean they are temporarily replaced by another register Interrupts are vectored, not polled Instruction Set Overview of ARM instruction encoding schemes and compare with AVR: In ARM, each instruction is encoded into a 32-bit instruction encoding scheme and have three operand instruction set. Opcodes have variable lengths, and some of those instructions are allowed to shift or rotate operands before execution by user. Some ARM processors also use Thumb instructions, which may be 16 or 32 bits long. AVR used 16-bit or 8-bit instruction and can have two operands.
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Describe the function and operation of ARM’s predicate instructions: Conditional execution is and instruction set architecture feature that is able to predict every instruction. To skip unnecessary branches, ARM provides instruction that compares with CPSR and branch when necessary. Compare the instruction used for stack operations in ARM and AVR processor: When pushing and popping registers, AVR can only push or pop a single register in one instruction, however ARM can push or pop multiple registers in one instruction. In AVR, stack pointer need to be read, modified and then written back when the user wants to change it. The reason is that it is stored in an I/O register. In ARM, the stack pointer can be modified directly since it is stored in a general register in R13. Describe how ARM processors access I/O registers and compare with AVR: AVR uses special instructions to access the I/O registers (such as in, out) since the separate I/O is used. In contrast, the memory-mapped I/O is used in ARM, hence it dose not provide special I/O instructions. Instead, normal load and
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