$1.8-$bit Register

Step$-$by$-$step Instructions:

Open Logisim and select Memory from the toolbar.

Add D Flip$-$Flops:

Add $8$ D flip$-$flops $($found in the "Memory" category$).$

Place them side by side, each representing one bit of the $8-$bit register.

Add Input Pins:

Create $8$ input pins, one for each bit, and connect each pin to the D input of the corresponding flip$-$flop.

Add a Clock Signal:

Add a clock pin and connect it to the clock input of all $8$ flip$-$flops.

Add a Load Enable:

Use an $8$:$1$ Multiplexer $($from the "Plexers" category$).$

Connect the current output Q of each flip$-$flop and the corresponding input bit to the multiplexer.

Use the Load Enable as the control input for the multiplexer.

Connect the output of the multiplexer to the D input of each flip$-$flop.

Add a Reset Signal:

Use an OR Gate for each flip$-$flop$$s output.

Connect the Reset signal to one input of each OR gate.

Connect the OR gate$$s output to the flip$-$flop$$s reset input.

$2.8-$bit Adder

Step$-$by$-$step Instructions:

Select Arithmetic from the toolbar and add an Adder:

Drag and drop an $8-$bit adder from the "Arithmetic" library.

If you want to manually create the adder:

Use $8$ full$-$adders $($from the "Gates" category or create one with AND, OR$,$ and XOR gates$).$

Chain the carry$-$out of one full$-$adder to the carry$-$in of the next.

Add Input Pins:

Add two $8-$bit input buses $($A and B$)$ and connect them to the adder$$s inputs.

Add Carry$-$in and Carry$-$out:

Add a carry$-$in pin and connect it to the carry$-$in of the first full$-$adder.

Add a carry$-$out pin to display the final carry.

$3.8-$bit Two's Complement Circuit

Step$-$by$-$step Instructions:

Add NOT Gates:

Drag $8$ NOT gates from the "Gates" library.

Connect each bit of the $8-$bit input to a NOT gate to invert the bits.

Add an Adder:

Add an $8-$bit adder to perform the addition of $1$ to the inverted bits.

Connect Components:

The output of the NOT gates $($inverted bits$)$ should be connected to the first input of the adder.

Connect a constant $00000001$ to the second input of the adder.

Add Output Pins:

Connect the adder$$s output to an $8-$bit output pin.

$4.8-$bit Zero Detector

Step$-$by$-$step Instructions:

Add OR Gates:

Use $8$ OR gates and cascade them to check if any bit is $1.$

For $8$ bits:

Combine bits $03$ with one $4-$input OR gate.

Combine bits $47$ with another $4-$input OR gate.

Combine these two outputs with a $2-$input OR gate.

Add a NOT Gate:

Connect the final OR gate$$s output to a NOT gate.

The NOT gate will output $1$ if all inputs are zero.

Add Input and Output Pins:

Add an $8-$bit input bus and connect it to the OR gates.

Connect the NOT gate$$s output to a $1-$bit output pin. Create in logism or hand draw. PART B $(50$ points$)$

Build any other $8-$bit circuits you wish that you think would be useful in a computer.