Registers and Buses Definitions

Question 1

MDR (MBR)

Answer 1

Memory Data Register - contains data or instructions fetched by memory during fetch-cycle

Question 2

MAR

Answer 2

Memory Address Register - contains the address of the instruction that is currently being fetched

Question 3

CIR

Answer 3

Current Instruction Register - holds data or instruction while it is being decoded

Question 4

Register

Answer 4

A high speed, fast access storage area in the memory used by the processor in the FE cycle

Question 5

Address Bus

Answer 5

Carries the address of instructions and/or data

Question 6

Bus

Answer 6

Made of wires - they just contain bits that represent what they carry

Question 7

Data Bus

Answer 7

Carries data or instructions

Question 8

Control Bus

Answer 8

Carries signals referring to a variety of operations e.g read from memory, write to memory

Question 9

ACC

Answer 9

Accumulator - contains the result of the instruction currently being executed

Question 10

PC

Answer 10

Program Counter - contains the address of the next instruction

Question 11

SR

Answer 11

Status register