HLT
Control Word : A control word is a word whose individual bits represent various control signals. Micro-routine : A sequence of control words corresponding to the control sequence of a machine instruction constitutes the micro-routine for that instruction.
The step of the machine cycle that translates an instruction into a form the processor can understand is called the decode phase. During this phase, the instruction fetched from memory is interpreted by the control unit, which determines the necessary actions and the data required for execution. This involves converting the instruction into signals that can control the processor's operations, allowing it to perform the specified task.
A pseudo-op is an assembly language instruction that specifies an operation of the assembler i.e about the base register & its contents e.g. USING instruction. On the other hand, a machine-op instruction. That represents a machine instruction to the assembler e.g. BR instruction is a machine-op instruction
an instruction cycle may consist of a number of machine cycles.
halt,DI (disable intrupts ),EI (enable intrupts),NOP(do nothing)
To add a new machine language instruction to an processor instruction set, you need to replace the microcode of the processor.
It depends on whether the machine code is one, two, or three bytes long, and on whether or not the instruction transferred control to another location. In the case of a non-jump single byte instruction, the PC will have a value of 2060H after the instruction is complete, and it will be 2061H or 2062H after a two or three byte instruction. In the case of a jump, call, or interrupt, the PC will depend on the instruction.
No. Generally, one instruction in a high level language corresponds to many instructions in machine language.
Each time the CPU executes an instruction, it takes a series of steps. The complete series of steps is called a machine cycle. A machine cycle can be divided into two smaller cycles. These are instruction cycle and execution cycle. Instruction cycle: In instruction cycle CPU takes two steps-- 1. Fetching: Before the CPU can execute an instruction, the control unit must retrieve or fetch a command or data from the computer's memory. 2. Decoding: Before a command can be executed, the control unit must decode the command into instruction set. Execution cycle: In execution cycle CPU also takes two steps-- 1. Executing: When the command is executed, the CPU carried out the instructions in order by converting them into macrocode. 2. Storing: The CPU may be required to store the result of an instruction in memory.
To calculate the number of machine cycles and opcode fetches for any instruction, you need to refer to the architecture's documentation, which outlines the instruction set and the corresponding cycles for each instruction. Typically, an opcode fetch counts as one machine cycle, and the total machine cycles for an instruction will depend on its complexity and any additional operations it requires, such as data fetches or memory accesses. Analyze the instruction's microarchitecture to determine the number of cycles needed for its execution, including any potential delays or dependencies.
microinstruction: An instruction that controls data flow and instruction-execution sequencing in a processor at a more fundamental level than machine instructions. Note: A series of microinstructions is necessary to perform an individual machine instruction.a micro instruction specifies one or more micro oprations for the system.
control unit