Practice question · Put in order
A two-bit counter holds 00 and increments on every clock edge, wrapping after its largest value. Order the values it holds after the next four edges.
- 11
- 10
- 01
- 00
Hints
- Add one in binary each time, and remember the register is only two bits wide.
- After the largest two-bit value the next increment cannot grow, so it must wrap.
Show the answer
- 01
- 10
- 11
- 00
Why
00 becomes 01, then 10, then 11, then wraps to 00 after four edges, a two-bit counter has a period of four. Expecting 100 after 11 is the fixed-width slip; the carry out of the top bit has nowhere to go and is discarded.
Practise Flip-Flops and Registers
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