Study Guide #2

Question 1

What is a combinational circuit?

Answer 1

circuit with more than one output

Question 2

MUX operations

Answer 2

select lines determine which input goes to output. Select lines represent binary form of output #.

Question 3

DEMUX operations

Answer 3

select lines determine which output the input goes to. Select lines represent binary form of output #.

Question 4

MUX uses

Answer 4

• implement boolean functions
• implement truth table

Question 5

Encoder operations

Answer 5

receives one high input and outputs the binary form through the access lines.

Question 6

Decoder operations

Answer 6

receives binary input of number through access lines and outputs to corresponding output line.

Question 7

Which Encoder/Decoder has an enable line?

Answer 7

Decoder

Question 8

Which of the four chips (MUX, DEMUX, Encoder, and Decoder) are the same just a different view?

Answer 8

DEMUX and Decoder

Question 9

How to implement boolean function using MUX

Answer 9

Draw MUX according to number of variables (ex. A,B,C = 3 seclect lines), then tie each input line from function to power and ground

Question 10

How is a decoder used to implement a boolean function?

Answer 10

same way as MUX

Question 11

Explain the SR latch

Answer 11

sets and resets circuit

Question 12

What is the problem with the SR latch?

Answer 12

invalid when both inputs are high

Question 13

Explain the clocked SR latch

Answer 13

timed set and reset

Question 14

What is the problem with the clocked SR latch?

Answer 14

When clock is high, it can change status multiple times

Question 15

JK flip-flip operation

Answer 15

set and reset with added protection

Question 16

SR flip-flop operation

Answer 16

set and reset

Question 17

D flip-flip operation

Answer 17

hold data

Question 18

T fliop-flop operation

Answer 18

stay same or inverse

Question 19

SR flip-flip characteristic table

Answer 19

0 0 Q(T)
0 1 0
1 0 1
1 1 NOT ALLOWED

Question 20

JK flip-flop characteristic table

Answer 20

0 0 Q(T)
0 1 0
1 0 1
1 1 Q’(T)

Question 21

D flip-flip characterictic table

Answer 21

0 0
1 1

Question 22

T flip-flop characteristic table

Answer 22

0 Q(T)
1 Q’(T)

Question 23

JK flip-flop excitation table

Answer 23

J K Q(T) Q(T+1)
0 0 0 X
0 1 1 X
1 0 X 1
1 1 X 0

Question 24

How to convert JK flip-flop into D flip-flop

Answer 24

Pass D into J, then use inverter to pass D’ into K

Question 25

What is a sequential circuit?

Answer 25

Digital circuit that contains atleast one flip-flop

Question 26

Register definition

Answer 26

consists of n flip-flips together with combinational control circuit
capable of storing n bits

Question 27

Problem with traditional register

Answer 27

always loading

Question 28

Normal registers contain

Answer 28

clock, inputs, D flip-flops, outputs

Question 29

Parallel registers contain

Answer 29

clock, inputs, load, AND gates, OR gates, D flip-flop, outputs

Question 30

shift register

Answer 30

goes right to left or left to right depending on right or left shift.

Question 31

registers use which flip-flops

Answer 31

D flip-flops

Question 32

Sequential circuits use which flip-flops

Answer 32

JK flip-flops

Question 33

figure 2.9 represents

Answer 33

bidirectional shift register with parallel load

Question 34

RAM characteristics

Answer 34

Volatile - all memory is lost when power is lost
stores words (power of 2) - all words have same size (multiple of 8)
Internal structure is specified by # of words and word size - each word has an address

Question 35

ROM characteristics

Answer 35

non-volatile - keeps data after power loss
performs only READ
contents of ROM is loaded during manufacturing

Question 36

what size is 2716 EPROM

Answer 36

2k x 8

Question 37

How many address lines and data lines does the Z80 CPU chip have

Answer 37

8 data lines, 16 address lines

Question 38

Which RAM/ROM had read/write control line?

Answer 38

RAM

Question 39

Lab 4: which sequential circuit did you have to build?

Answer 39

when Y is 1, the circuit counts from 0 - 3 then repeats, when Y is 0, circuit stays in current state

Question 40

Lab 4: what was the purpose of the input line?

Answer 40

control if circuit counts or stays at current state

Question 41

Lab 4: what was the extra credit?

Answer 41

Implement the BCD encoder to show the binary number on the 7 segment LED display

Question 42

Lab 5: What type of flip-flip circuit did we build?

Answer 42

SR latch

Question 43

Lab 5: did it change on rising edge or falling edge of clock?

Answer 43

rising edge (from 0 - 1) not falling edge (1 - 0)

Question 44

Lab 5: What was the extra credit?

Answer 44

build SR master-slave flip-flop