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Old 2005-09-16, 21:15   #6
RMAC9.5
 
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Jun 2003

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Cheesehead's answer is partly correct but incomplete (as he left out the last 6 "digits"). IBM's hexadecimal BCD code has 16 characters, 0 - 9 and A - F.
Here are the missing characters:
A (decimal) = 1010 (BCD)
B (decimal) = 1011 (BCD)
C (decimal) = 1100 (BCD)
D (decimal) = 1101 (BCD)
E (decimal) = 1110 (BCD)
F (decimal) = 1111 (BCD)

Consequently, 1011 0011 1100 0100 = B 3 C 4 and is considered by IBM mainframe programmers as a 4 digit hexadecimal number which can be added, subtracted, multiplied, etc. like any other number. This is where, I think, the expression "A + 1 = B" came from (e.g. 1010 + 0001 = 1011 or A+1 = B).

Last fiddled with by RMAC9.5 on 2005-09-16 at 21:29
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