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Browse Prior Art Database

Data Packing and Unpacking Means

IP.com Disclosure Number: IPCOM000097463D
Original Publication Date: 1962-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Tilem, JY: AUTHOR

Abstract

The drawings A, B, C and D show, a coding technique which can be reduced to And and Or circuitry. Each of the above drawings represents an eight bit byte of data having bit positions 1 through 8. The coding technique permits a single six-bit alpha character or two four bit numeric characters within a single eight bit byte.

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Data Packing and Unpacking Means

The drawings A, B, C and D show, a coding technique which can be reduced to And and Or circuitry. Each of the above drawings represents an eight bit byte of data having bit positions 1 through 8. The coding technique permits a single six-bit alpha character or two four bit numeric characters within a single eight bit byte.

The packed or unpacked condition of the byte is indicated by the 1 bit position in the byte having a 1 or 0, respectively. In A, a single alpha character is shown. It is indicated by having a 0 bit in the 1 bit position of the byte. The 2 bit position is not used but contains a 0 bit.

On the other hand, if it is desired to have two four bit decimal characters packed in a single byte, then the 1 bit position of the byte contains a 1 bit. Drawings B, C and D illustrate byte conditions having two packed decimal characters therein.

In B, each of the decimal digits is represented symmetrically by three bits. Since three bits can only represent the decimal digits 0 through 7, this packed configuration can only represent decimal numbers 0 through 77, exempting the decimal values below 77 having an 8 or 9 in their units positions, such as 8, 9, 18, 19, 28, 29, 38, 39, 48, 49, 58, 59, 68 or 69. In this case, the 2 bit position of the byte is used as a symmetry indicator. It contains a 0 bit to indicate symmetrical three bit decimal characters in respective byte positions 3, 4, 5 and 6, 7, 8.

Drawings C and D illustrate unsymmetrical conditions for the number of bit positions used t...