4-2/4-3 MARIE

Question 1

Which of the following is an example of unconditional branching in MARIE’s architecture?

Answer 1

JUMP

Question 2

Which of the following CPU components is responsible for fetching and decoding instructions?

Answer 2

The Control Unit

Question 3

Decoding the instruction must always take place before an instruction is executed.

Answer 3

True

Question 4

The JUMP instruction will change the value stored in which location?

Answer 4

Program Counter

Question 5

Which of the following are the components of an instruction in MARIE’s architecture?

Answer 5

Address, Opcode

Question 6

In MARIE’s architecture, explain what action is taken by the following RTN statement.

IR <– M[MAR]

Would the statement be categorized as a step in fetch, decode, or execute?

Answer 6

It is moving an instruction from MM into the IR. It is part of fetch.

Question 7

What data would the memory address register (MAR) hold in MARIE? Where would data placed in the MAR be sent after being written into the register?

Answer 7

The MAR holds a memory address. The address is always sent via a direct connection to main memory when reading or writing main memory.

Question 8

Evaluate the following instruction (MARIE architecture) to determine its human-readable opcode (example: LOAD) and the hexadecimal number of the specified memory address. An example answer format is “JUMP 123”.

0011001000011110

Answer 8

0011 0010 0001 1110

0011 = add x

0010 = 2

0001 = 1

1110 = E

ADD 21E

Question 9

In one or two sentences, what does following simple program do (MARIE architecture)?
LOAD 100
STORE 200
LOAD 300
STORE 400
ADD 200
HALT

Answer 9

The program moved a stored value from 100 to 200, then moves a stored value from 300 to 400. Afterward, it adds the stored value at 200 to the AC value (300/400) and halts.