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Justify RST instruction can be called 1 byte Call instruction?
The RST instruction is a 1 byte opcode with a 3 bit imbedded operand. There are 8 different RST instructions. Each pushes the PC on the stack, and loads the PC with the operand's value times 8. (0H, 8H, 10H, 18H, etc.)Pushing the PC on the stack and loading a new value into the PC is exactly what a CALL instruction does, so the RST instruction is a 1 byte CALL instruction. The difference between RST and CALL is that CALL is a 3 byte instruction which can go anywhere in memory in one instruction.
Which register deals with sequencing the execution of instructions?
The register that deals with sequencing the execution of instructions is the Program Counter (PC). The PC holds the address of the next instruction to be executed in the program sequence. As each instruction is fetched and executed, the PC is updated to point to the subsequent instruction, ensuring the correct order of execution.
What part of the processor indicates which machine instruction in next in line for execution?
The part of the processor that indicates which machine instruction is next in line for execution is called the Program Counter (PC). The Program Counter holds the memory address of the next instruction to be fetched and executed. After the current instruction is executed, the PC is updated to point to the subsequent instruction, ensuring the sequential flow of execution in a program.
If the 8085 MPU fetches 2057H what is the content of PC?
The instruction 20H is RIM (Read Interrupt Mask). The instruction 57H is MOV D,A. The contents of PC after these two instruction will be 2 greater than it was before starting.
What is the use of Interrupt vector table of 8086 microprocessor?
The interrupt vector table in the 8085 is a region of low memory that contains the target addresses for the RST instructions. RST can be invoked by the program, by an INTR request which provides an RST x instruction in response to INTA, or by one of the four direct interrupt pins, TRAP, RST5.5, RST6.5, and RST7.5 Each of these interrupt sequences place the PC on the stack, and then execution goes to one of the vectors. The vectors are as follows... RST 0: 0000H RST 1: 0008H RST 2: 0010H RST 3: 0018H RST 4: 0020H TRAP: 0024H RST 5: 0028H RST5.5: 002CH RST 6: 0030H RST6.5: 0034H RST7: 0038H RST7.5: 003CH
What holds the address of the current instruction in the control unit?
The address of the current instruction in the control unit is held by a register called the Program Counter (PC). The PC keeps track of the memory location of the next instruction to be executed in a program. As each instruction is fetched and executed, the PC is incremented to point to the subsequent instruction. This allows the control unit to manage the flow of execution in a sequential manner.
What is execute cycle in microprocessor?
The sequence of operations that the cpu has to carry out while execution is called instruction cycle. 1:- Read an Instruction 2:- Decode the instruction 3:- Find the address of operand 4:- retrieve an operand 5:- perform desired operation 6:- find the address of destination 7:- store the result into the destination
How an instruction is executed in sap-1?
In SAP-1 (Simple Asynchronous Processor), instruction execution involves a series of steps. First, the instruction is fetched from memory using the Program Counter (PC), which points to the address of the next instruction. The fetched instruction is then decoded to determine the operation and the operands involved. Finally, the execution phase carries out the operation, which may involve reading from or writing to memory, updating registers, or performing arithmetic operations. This cycle is repeated for each instruction until the program completes.
What is instruction pointer?
The instruction pointer (IP), also known as the program counter (PC) in some architectures, is a special register in a computer's CPU that tracks the address of the next instruction to be executed in a program. As the CPU processes instructions sequentially, the instruction pointer is updated to point to the subsequent instruction, allowing for the orderly execution of code. In the case of control flow changes, such as jumps or function calls, the instruction pointer can be modified to point to a different location in memory. This mechanism is essential for the sequential flow of program execution.
What fetches each instructions?
In a computer's CPU, the instruction fetch stage retrieves instructions from memory. The program counter (PC) holds the address of the next instruction to be executed, which is used to access memory. Once fetched, the instruction is then typically decoded and executed in subsequent stages of the instruction cycle. This process is essential for the sequential execution of programs.
How many interrupts in 8085 microprocessor?
The processor has 5 interrupts. They are presented below in the order of their priority (from lowest to highest):INTR is maskable 8080A compatible interrupt. When the interrupt occurs the processor fetches from the bus one instruction, usually one of these instructions:One of the 8 RST instructions (RST0 - RST7). The processor saves current program counter into stack and branches to memory location N * 8 (where N is a 3-bit number from 0 to 7 supplied with the RST instruction).CALL instruction (3 byte instruction). The processor calls the subroutine, address of which is specified in the second and third bytes of the instruction.RST5.5 is a maskable interrupt. When this interrupt is received the processor saves the contents of the PC register into stack and branches to 002Ch (hexadecimal) address.RST6.5 is a maskable interrupt. When this interrupt is received the processor saves the contents of the PC register into stack and branches to 0034h (hexadecimal) address.RST7.5 is a maskable interrupt. When this interrupt is received the processor saves the contents of the PC register into stack and branches to 003Ch (hexadecimal) address.Trap is a non-maskable interrupt. When this interrupt is received the processor saves the contents of the PC register into stack and branches to 0024h (hexadecimal) address.All maskable interrupts can be enabled or disabled using EI and DI instructions. RST 5.5, RST6.5 and RST7.5 interrupts can be enabled or disabled individually using SIM instruction.
Which register in 8086 contains the address of the next instruction to be fetched?
program counter holds the address of the next instruction.
