Question

Number of pulses needed to change the contents of a 8-bit up counter from10101100 to 00100111 (right most bit is the LSB) are _______

• A. 123

Answer 1

The correct option is A 123
In a $2^8$ counter, the range would be from 0-255. Hence to go from 10101100${\left(172\right)}_{10}$ to 00100111${\left(39\right)}_{10}$ the counter has to go initially 172 to 255 and then from 0 to 39. Hence to go from 172 to 255, 255 -172 = 83 clock pulses would be required.
From 255 to 0, again 1 clock pulse would be required.
Then from 0 to 39, 39 clock pulses would be required.
Hence in total 83+1+39 =123 clock pulses would be required.