How many pulses are needed to change the contents of a 8-bit up counter from 10101100 to 00100111 (rightmost bit is the LSB)?
(A) 134
(B) 133
(C) 124
(D) 123


Answer: (D)

Explanation: 8 bit Counter range 0-255

To go from 10101100 (172) to 00100111 (39)

• first counter will move from 172 to 255(255-172=83)
• 255 to 0=1 pulse
• and then  0 to 39(39-0=39).

Total=83+1+39=123

So answer is D

 

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