Attached.

EEE 120
Simulation Lab 4 Answer Sheet
The Microprocessor
Name:__________________________
Date:________________________

Task 4-1: Build the Addressing Logic
Include a picture of your Logisim addressing logic circuit here:

Task 4-2: Build a 4-Bit ROM Memory Cell
Include a picture of your Logisim 4-bit ROM circuit here:

1

Task 4-3: Build 4-Bit Output Port
Include a picture of your Logisim 4-bit output port circuit here:

Test your circuit and record the results in Table 1.

Data Bus
(4-bit binary)
0101
0101
0101

Table 1
Memory
Write
Select
0
0
0
1
1
0
2

Q
0
0
0

0101

1

1

5

Task 4-4: Build the 4-Bit RAM Cell
Include a picture of your Logisim 4-bit RAM circuit here:

Test your circuit and record the results in Table 2. Include a picture of your Logisim 4-bit RAM circuit
testing set up.
Table 2
Data Bus
(4-bit binary)
0101
0101
0101
0001
0101
0101

Write
0
1
0
0
1
0

Memory
Select
0
1
1
1
1
1

Q {between register
and buffer}
0
5
5
5
1
1

Read
0
0
1
0
0
1

3

Data Bus {after
buffer}
0
0
5
5
1

Task 4-5: Build the Brainless Central Processing Unit
Include a picture of your Logisim Brainless Central Processing Unit circuit here:

Task 4-6: Build the Brainless Microprocessor
Include a picture of your Logisim brainless microprocessor circuit here:

4

Task 4-7: Testing and Controlling the Brainless Microprocessor
Follow steps 1 through 3 outlined in the laboratory manual to test your brainless microprocessor circuit.
It might be helpful to review the ALU Function Table from Sim lab 3. Table 3 is an example, for the ADD
command, of how to fill out tables to record the values of the control lines during every clock cycle.
Table 3
Instruction [ Add operand to Accumulator (ACC) ]
Control Line

Write

Value
Address of
operand
0

Read

1

ACC to Data Bus

0

Load ACC

1

/~A_Only

1

/~Invert

1

Logic/~Arith

0

4-bit Binary Keyboard (Address Bus)

5

For all of the instructions you performed (i.e. Subtract, Load ACC, etc.) record the values of the control
line...