# DC/RC problem

Discussion in 'Homework Help' started by Hazard111, Jan 2, 2015.

1. ### Hazard111 Thread Starter New Member

Jan 1, 2015
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How to see if 5 bit number which can be in DC or RC format is greater than 9

2. ### MikeML AAC Fanatic!

Oct 2, 2009
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What is DC or RC format?

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3. ### Hazard111 Thread Starter New Member

Jan 1, 2015
13
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Digit Complement (Ones' complement)/DC

4. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
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Write out a truth table of the five bits for all positive numeric values > zero. Use Combinatorial logic (sum-of-products) to create a single output which is true for 9<=value<=15.

5. ### WBahn Moderator

Mar 31, 2012
20,258
5,759
I think you probably mean (or the author probably meant) "diminished radix complement" for DC.

Break it down into pieces.

What does the msb tell you in either case?

Assuming that the number in question is positive, how can you use just the lower four bits to determine if the value is greater than 9?

What would be the result if you subtract 9 from the number?