Microprocessor · Unit 3 · 3 hrs
Instruction Cycle
Exam-focused notes for Instruction Cycle (Microprocessor, CSC167): what the TU syllabus asks and how it has actually been tested, with 7 solved past questions from this unit.
What this unit covers
- Fetch Operation and Timing Diagram
- Execute Operation and Timing Diagram
- Instruction Cycle
- Machine Cycle
- T-States
- T-States
- Memory Interfacing
Machine Cycle
What is ALE signal? Draw a timing diagram for LDA 5000H instruction and explain the machine cycles involved.[10]
--- ALE (Address Latch Enable) is a control signal generated by the 8085 microprocessor. It is an active HIGH output signal that is used to demultiplex the lower-order address bus from the data bus. The 8085 has a multiplexed address/data bus. The lower 8 b...
Full solved answer →Instruction Cycle
Explain instruction cycle, machine cycle and T-states. Draw timing diagram of fetch and execute of LDA instruction with brief description.[10]
--- The instruction cycle is defined as the total time required to fetch and execute an entire instruction. An instruction cycle consists of two parts: - Fetch Cycle (FC): The CPU fetches the opcode from memory. The address stored in the Program Counter (PC...
Full solved answer →What is instruction cycle? Draw timing diagram of MOV A, B. Make necessary assumptions.[10]
--- Instruction Cycle is defined as the total time required to fetch and execute an entire instruction. From the notes: "The time required to execute and fetch an entire instruction is called instruction cycle." The instruction cycle is given by: $$IC = FC ...
Full solved answer →Explain instruction cycle, machine cycle and T-states. Draw timing diagram of IN instruction with brief description.[10]
--- The time required to fetch and execute an entire instruction is called the instruction cycle. An instruction cycle consists of two parts: - The CPU fetches the opcode from memory using the address stored in the Program Counter (PC). - The fetched opcode...
Full solved answer →Explain instruction cycle, machine cycle and T-States. Draw timing diagram of STA instruction. Make necessary assumptions.[10]
--- The time required to fetch and execute an entire instruction is called an instruction cycle. An instruction cycle consists of two parts: - The CPU fetches the opcode from the memory location pointed to by the Program Counter (PC). - The fetched opcode i...
Full solved answer →Difference between instruction cycle and machine cycle. Draw timing diagram of MVI A, 32 H. [5]
--- Basis Instruction Cycle Machine Cycle --------- Definition Time required to fetch and execute an entire instruction Time required to access memory or I/O device once Composition Consists of one or more machine cycles Consists of 3 to 6 T-states Formula ...
Full solved answer →Memory Interfacing
What is mean by memory interfacing? Explain the address decoding process in the 8085 microprocessor with 3 to 8 decoder. [5]
Memory interfacing refers to the process of connecting memory chips (RAM/ROM) to the microprocessor so that the CPU can read from and write to those memory locations correctly. It involves properly connecting the address bus, data bus, and control bus of th...
Full solved answer →Make Unit 3 stick
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