Browse Prior Art Database

Vary Operation

IP.com Disclosure Number: IPCOM000097852D
Original Publication Date: 1961-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 3 page(s) / 52K

Publishing Venue

IBM

Related People

Blaauw, GA: AUTHOR

Abstract

In certain variable field-length data processing machines, it is expedient to deal with bits, bytes and fields as basic information units. The bit is the elemental binary information entity signifying by its absence the value 0 or by its presence the value 1. The byte is normally a group of four bits and is the basic unit for logical processing. A byte in binary coded decimal notation signifies the decimal values 0... 9. A byte in binary or hexadecimal notation signifies decimal values 0... 15. The machine memory normally references to a word which is a contiguous series of sixteen bytes 0... 15 and has a distinctive address. The memory connects to other sections of the data processing machine a full word at a time.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Vary Operation

In certain variable field-length data processing machines, it is expedient to deal with bits, bytes and fields as basic information units. The bit is the elemental binary information entity signifying by its absence the value 0 or by its presence the value 1. The byte is normally a group of four bits and is the basic unit for logical processing. A byte in binary coded decimal notation signifies the decimal values 0... 9. A byte in binary or hexadecimal notation signifies decimal values 0... 15. The machine memory normally references to a word which is a contiguous series of sixteen bytes 0... 15 and has a distinctive address. The memory connects to other sections of the data processing machine a full word at a time.

A field is a variable number of bytes not greater than the number of bytes in a memory word. The field may start and terminate at various byte positions within a word, and may cross word boundaries. Addressing a field, therefore, requires a word address directed to a memory location and a byte address which is directed to a register. During byte processing left to right, bytes are referenced in ascending order 0... 15 according to a byte counter. As the byte counter goes from 15 to 0, a carry is produced which increments the word address. Byte 15 of word 2002 is thus adjacent to byte 0 of word 2003 and can be part of the same field.

In the variable field-length format chosen, termination of the field is by a limit address. Fourteen-byte Field K, diagrammed above, is thus specified by word address 2002, byte address 12 and limit address 9. K crosses the word boundary between memory locations 2002 and 2003. Also shown are Field L (2003-14-6) which also crosses a word boundary and Field M (2005-1-14) which lies fully within word 2005.

Certain processing applications require address modification by a word increment and a byte increment. Since the field length is - unchanged by the address modification, the limit increment is identical to the byte increme...