last day Flashcards
What is the MAR and what is it used for?
The MAR (Memory Address Register) is a special register that is used to hold the address in a memory transfer.
What is the MDR?
The MDR (Memory data register) is a special register that is used to hold the data in a memory register
What does a typical instruction cycle consist of?
- Instruction fetch (IF) - fetch the instruction from memory
- Instruction decode (ID) - decode the instruction
- Operand(s) fetch (OF) - fetch the operatnds. This step is not always required, and depends on addressing modes being used
- Instruction Execute(IE) - execute the instruction
- Store Result/Write Back (WB) - write results
- Process Interrupts - process any pending interrupt requests; not always required
What are micro-opertions?
Typically the smallest unit of work performed by the CPU
Their role is to control the operations of the CPUs components
Provides a set of control signals to one or more of the CPU components
What are the steps to load a word from a main memory
- Calculate the address to be accessed and denote it by addr
- Store the address addr into the memory address register (MAR)
- Control unit (CU) sends a “read” signal to the memory. The data requested is placed into the memory data register (MDR)
- Read the data from MDR
What are the steps to store a word x to a main memory?
- Calculate the address to be accessed and denote it by addr
- Store the data value x to the memory data register (MDR)
- Store the address addr into the memory address register (MAR)
- Control unit (CU) sends a “write” signal to the memory. The data requested is placed into the meory after some time has passed
What are the two possible solutions for interfacing with memory?
What are the steps that constitute one instruction cycle?
What are the micro operations for the following:
