(a) Complete the table to compare the BCD and pure binary representations of each denary number. Denary BCD Pure binary 39 85 127 [4]

Assessment: Computer Science 0478 | Paper 1 Mock 01 | Computer Systems Subject: Computer Science - 0478

Question 1 Report

(a) Complete the table to compare the BCD and pure binary representations of each denary number.

DenaryBCDPure binary
39  
85  
127  

[4]

Answer Details

(a) Comparing BCD and pure binary for each denary number:

Row 1: Denary 39

  • BCD: 3 = 0011, 9 = 1001. BCD = 0011 1001.
  • Pure binary: 39 = 32 + 4 + 2 + 1 = 00100111.

Row 2: Denary 85

  • BCD: 8 = 1000, 5 = 0101. BCD = 1000 0101.
  • Pure binary: 85 = 64 + 16 + 4 + 1 = 01010101.

Row 3: Denary 127

  • BCD: 1 = 0001, 2 = 0010, 7 = 0111. BCD = 0001 0010 0111 (12 bits needed).
  • Pure binary: 127 = 64 + 32 + 16 + 8 + 4 + 2 + 1 = 01111111 (8 bits).
DenaryBCDPure binary
390011 100100100111
851000 010101010101
1270001 0010 011101111111

Notice that for 127, BCD requires 12 bits while pure binary needs only 8, illustrating BCD's lower storage efficiency. [4]

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