Content deleted Content added
VampWillow (talk | contribs) m l/c |
→Higher density encoding: add IBM and BCD |
||
Line 20:
If a decimal digit requires four bits, then three decimal digits require 12 bits. However, since 2<sup>10</sup>>10<sup>3</sup>, if three decimal digits are encoded together then only 10 bits are needed. Two such encodings are
''Chen-Ho encoding'' and ''densely packed decimal''.
==IBM and BCD==
[[IBM]] used the terms '''Binary-Coded Decimal''' and '''BCD''' for six-bit codes that represented numbers, upper-case letters and special characters. Some variation of BCD was used in most early IBM computers, including the [[IBM 1400 series]] and non-decimal members of the [[IBM 700/7000 series]]. With the introduction of [[System/360]], IBM replaced BCD with 8-bit [[EBCDIC]].
Bit positions in BCD were usually labled ''B, A, 8, 4, 2'' and ''1.'' For encoding digits, ''B'' and ''A'' were zero. The letter '''A''' was encoded ''(B,A,1).''
==External links==
| |||