COMPUTER ARCHITECTURE AND ORGANIZATION: An ... - IIUSA

0/0
A
input/outputs
0/0
1/0
1/0
C B
1/0
0/0
1/1
D E
0/0 0/1
1/0
Present
State
A
B
C
D
E
Input (x)
0 1
(A-13) Design an FSM using D flip-flops and the smallest possible ROM for a remote control that
operates a TV:0, a VCR:1, and a CATV:2 device. The user selects a device by pressing the corresponding
key. Once a device is selected, the user can increase the channel number (3) or decrease the
channel number (4). The input (0, 1, 2, 3, or 4) is repeated on the corresponding output port (one for
each device), except for 0, 1, and 2 which produce 0's at all outputs. (Hint: The STD is easier to draw
if you use base 10.)
(A-14) Consider the following circuit which contains a 3-bit register and a black box with some
combinational logic:
CLOCK
D1
Q1
D2
Q2
D3
Q3
Black box of
combinational logic
The initial state of the circuit is Q 1 Q 2 Q 3 = 000. The circuit generates the sequence
(010) → (110) → (001) → (001) → ... → (001)
on successive clock cycles. Which of the following sets of equations are implemented by the
combinational logic in the black box? The prime symbol (') in X' has the same meaning as an
overbar.