148. A Schmitt-trigger can be used as a
A. comparator only
B. square-wave generator only
C. flip-flop only
D. comparator, square wave generator or flip-flop

---

149. A 555 IC timer can be used to operate as
A. as monostable multivibrator
B. an astable multivibrator
C. a voltage controlled oscillator
D. all of the above

---

150. The number of levels in a digital signal is
A. one
B. two
C. four
D. ten

---

151. A device that converts from decimal to binary numbered is called
A. decoder
B. encoder
C. CPU
D. converter

---

152. Decimal 15 in binary system can be written as
A.1111
B.1110
C.1100
D.1000

---

153. If 4 in binary system is 100 then 8 will be
A.10
B.100
C.111
D.1000

---

154. Binary 1010 in decimal system is equaivalent to
A.13
B.I9
C.10
D.23

---