Question

Assume you are performing the calculation of (123)_10 - (3)_10. Answer questions (31) - (35) based on the following "Addition & Subtraction Unit" What is the value for c0? What is the value for s1? What is the value for a2? What is the value for b3? What is the value for x3? What is the hexadecimal (HEX) number displayed on the following abacus?

Answer 1

36)

Ones place : 0 in hex (0)

Tens place : 5*2 + 2*1 = 12 in hex (A)

Hundreds place : 5*2 + 5*1 = 15 in hex (F)

Thousands place : 5*1 + 4*1 = 9 in hex (9)

Ten thousand place : 5*1 + 1*0= 5 in hex (5)

Lakhs place : 3*1 + 5*0 = 3 in hex (3)

So hex value is 0x359FA0

34) a=1010 b=0011 so b3 =0

31) c0=a3 = 1

35) a3=1 b3=0

x3=a3 xor b3 = 1 xor 0 = 1

32)

x0= b0 xor a3 = 1 xor 1 = 0

a0 + x0 + c0 = 0 + 0 + 1 now s0 =1 , c1= 0

x1 = b1 xor a3 = 1 xor 1= 0

a1+c1+x1 = 1 + 0 + 1 now s1=0 , c2=1

Hence s1=0

33) a2=0 where a=1010