12-bit hollerith code and alphanumeric code?

Question

Can someone help me with this i basically don't know whats a hollerith or alphanumeric code and that too 12-bit?

Answer 1

12-bit hollerith code:

In 1896, Hollerith formed a company called the Tabulating Machine Company. This company developed a line of machines that used punched-cards for tabulation. After a number of mergers, the Tabulating Machine Company was formed into the International Business Machines Corporation, now referred to more commonly as IBM, Inc. We often refer to the punched-cards used in computer systems as Hollerith cards in honor of Herman Hollerith. The 12-bit code used on a punched-card is called the Hollerith code.

A Hollerith string is a sequence of 12-bit characters; they are encoded as two ASCII characters, containing 6 bits each: the first character contains punches 12, 0, 2, 4, 6, 8 and the second character contains

punches 11, 1, 3, 5, 7, 9; interleaving the two characters gives the

original 12 bits.  To make the characters printable on ASCII terminals,

bit 7 is always set to 0, and bit 6 is set to the complement of bit 5.

These two bits are ignored when reading Hollerith cards.

A device for translating a multibit input code into a desired multibit output code including a double-ended decoding circuit which converts the signals representing an input character into a single signal and apparatus which encodes this single signal into the signals representing a corresponding output character.

alphanumeric code:

Simply a code that uses both letters of the alphabet and numbers.

12-bit:

In binary (base 2) only 0 and 1 are used as count weight. Decimal (base 10) numbers 0 thru 9 are used.

A 12 bit decimal number is 100 000 000 000 and is read 100 Giga or one hundred thousand million.

In binary 12 bit is 1000000000 and each place is is a power of 2 so this number is 2^10 = 1024 decimal.

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