Computer Systems 4.1 &4.2

Notes for 4.1 and 4.2

Name the four main sub-systems of the von Neumann Architecture.

Memory, ALU (Arithmetic Logic Unit), Control Unit, and Input/Output System (I/O).

What is the "stored-program concept"?

The idea that program instructions are stored in the main memory during execution.

What are the three primary types of System Buses?

data Bus, Address Bus, and Control Bus.

What is the function of the Control Bus?

To carry the control signals and commands that synchronize operations between system components.

What term describes memory that loses its stored data when power is removed?

Volatile (This applies to Main Memory/RAM).

What unit within the CPU performs all arithmetic and logic operations?

The Arithmetic Logic Unit (ALU).

Which component is responsible for controlling the Fetch-Decode-Execute cycle?

The Control Unit (CU).

What mechanism allows an I/O device to pause the CPU's current operation because it needs attention?

An Interrupt.

What is the two-part structure of a typical CPU instruction?

The Op-Code (the operation) and the Operand (the address/data location).

Which register holds the address of the next instruction to be executed?

The Program Counter (PC).

Which register holds the address of the memory location currently being accessed (read/write)?

The Memory Address Register (MAR).

Which register holds the current instruction being processed?

The Instruction Register (IR).

During the Fetch stage, what is the primary role of the Program Counter (PC)?

Its address is copied to the MAR, and the PC is then incremented to point to the next instruction.

Which CPU component is responsible for interpreting the instruction during the Decode stage?

The Control Unit (CU).

Which CPU component performs the operation if the instruction is an arithmetic calculation during the Execute stage?

The Arithmetic Logic Unit (ALU)

What is the term for when the CPU's sequential execution is temporarily halted to deal with a high-priority event?

An Interrupt.