中原大學九十學年度碩士班入學招生考試

4月28日  第2節   電子系乙組 誠實是我們珍視的美德,
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科目:數位電路 (共2頁 第1頁)


注意:共計五大題。每大題 20 分。
1. Express each decimal number as an 8-bit number in two's complement number system.
(1) -34
(2) -99
(3) -125
(4) +101

2. Simplify each Boolean expression in minimum sum-of-products (SOP) form.
(1) A'B(C'D'+CD)+AB(CD'+CD)+AB'C'D
(2) (A'B'+AB')(CD+CD')

3. A majority function F(a,b,c) is generated in a combinational circuit. The output is equal to 1, if the input variables a, b, and c have more 1's than 0's. The output is 0 otherwise.
(1) Derive the truth table and the simplified Boolean equation for F(a,b,c).
(2) Implement F with a 4-to-1 MUX (multiplexer) shown below. Suppose that a is applied to Si, and b is applied to S0. In addition to the 4-to-1 MUX, you may use only 0, 1, NOT, OR, and AND gates.

4.

Minimize the number of states of the finite state machine as shown in the following state/output table.

Present State Next State

Output

z

x=0 x=1
A C B 1
B F E 0
C D F 1
D C G 1
E F B 0
F E D 0
G F G 0

(1) List the equivalence classes.
(2) Show the minimized state machine by using state/output table.

5. Design a binary counter with the following binary sequence: 0, 1, 2, 3, 4, 5, 6 and repeat. Use natural binary encoding and three JK flip-flops as memory elements.

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