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Quadrahex Coding

IP.com Disclosure Number: IPCOM000043162D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Bannon, RD: AUTHOR [+2]

Abstract

The method proposed utilizes binary number strings in a six-bit quadrahex code rather than a hexadecimal four-bit code. This results in fifty percent fewer characters to represent a binary string. While hexadecimal denotes a binary base of sixteen, quadrahex denotes a binary base of sixty-four. The code characters are shown in Fig. 1. For example, if used in a keyboard decoded register, the letter "m" would have a binary code of 010101 and an upper case "A" would have 101010. The advantages of utilizing the quadrahex coding system becomes evident in applications such as testing and debugging micro-code patterns used in random-access memory chip registers. In order to test a 72-bit matrix (64 data bits and 8 check bits), 576 ones or zeros are keyed in row by row to complete the matrix.

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Quadrahex Coding

The method proposed utilizes binary number strings in a six-bit quadrahex code rather than a hexadecimal four-bit code. This results in fifty percent fewer characters to represent a binary string. While hexadecimal denotes a binary base of sixteen, quadrahex denotes a binary base of sixty-four. The code characters are shown in Fig. 1. For example, if used in a keyboard decoded register, the letter "m" would have a binary code of 010101 and an upper case "A" would have 101010. The advantages of utilizing the quadrahex coding system becomes evident in applications such as testing and debugging micro-code patterns used in random-access memory chip registers. In order to test a 72-bit matrix (64 data bits and 8 check bits), 576 ones or zeros are keyed in row by row to complete the matrix. By using quadrahex coding, matrix coded words are keyed in automatically using only 96 key strokes instead of 576 strokes, as shown in Fig.
2. For example, the first row would require 12 key strokes: Y G U f 3 6 @ 8 @ 8 2 0. The next seven rows would be entered in a similar manner. The entire operation would require 96 key strokes as compared with 576. Another use of quadrahex coding would be for loading micro-code words. Typically, micro-code words are 18, 36 or 72 bits long. By using only 12 entries for each 72-bit string, loading, changing and debugging are efficiently improved using quadrahex. It has been found that using quadrahex coding to formulate testing pa...