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Most pocket calculators do all their calculations in BCD. The same argument applies when hardware of this type uses an embedded microcontroller or other small processor. Often, representing numbers internally in BCD format results in smaller code, since a conversion from or to binary representation can be expensive on such limited processors.
BCD (binary-coded decimal), also called alphanumeric BCD, alphameric BCD, BCD Interchange Code, [1] or BCDIC, [1] is a family of representations of numerals, uppercase Latin letters, and some special and control characters as six-bit character codes. Unlike later encodings such as ASCII, BCD codes were not standardized. Different computer ...
The Aiken code (also known as 2421 code) [1] [2] is a complementary binary-coded decimal (BCD) code. A group of four bits is assigned to the decimal digits from 0 to 9 according to the following table. The code was developed by Howard Hathaway Aiken and is still used today in digital clocks, pocket calculators and similar devices [citation needed].
Binary-coded decimal (BCD) is a binary encoded representation of integer values that uses a 4-bit nibble to encode decimal digits. Four binary bits can encode up to 16 distinct values; but, in BCD-encoded numbers, only ten values in each nibble are legal, and encode the decimal digits zero, through nine.
In computer science, the double dabble algorithm is used to convert binary numbers into binary-coded decimal (BCD) notation. [ 1 ] [ 2 ] It is also known as the shift-and-add -3 algorithm , and can be implemented using a small number of gates in computer hardware, but at the expense of high latency .
Densely packed decimal (DPD) is an efficient method for binary encoding decimal digits.. The traditional system of binary encoding for decimal digits, known as binary-coded decimal (BCD), uses four bits to encode each digit, resulting in significant wastage of binary data bandwidth (since four bits can store 16 states and are being used to store only 10), even when using packed BCD.
Adding BCD numbers using these opcodes is a complex task, and requires many instructions to add even modest numbers. It can also require a large amount of memory. [ 2 ] If only doing integer calculations, then all integer calculations are exact, so the radix of the number representation is not important for accuracy.
Six-bit BCD code was the adaptation of the punched card code to binary code. IBM applied the terms binary-coded decimal and BCD to the variations of BCD alphamerics used in most early IBM computers, including the IBM 1620 , IBM 1400 series , and non- decimal architecture members of the IBM 700/7000 series .