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Data Attribute Tables for Computer Systems

IP.com Disclosure Number: IPCOM000078490D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

Fierst, PE: AUTHOR [+2]

Abstract

This technique minimizes use of R/W storage while maintaining functional capability. Storage use is reduced by eliminating redundant data descriptions in instructions. Each instruction operand, rather than directly addressing the data field, instead refers to an entry in a table. The table entry contains the location and the attribute of the data to be operated upon. The instruction stream is, therefore, independent of the actual location or description of the data, and each instruction is concerned only with a logical function, i.e., ADD, SUBTRACT, COMPARE, etc.

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Data Attribute Tables for Computer Systems

This technique minimizes use of R/W storage while maintaining functional capability. Storage use is reduced by eliminating redundant data descriptions in instructions. Each instruction operand, rather than directly addressing the data field, instead refers to an entry in a table. The table entry contains the location and the attribute of the data to be operated upon. The instruction stream is, therefore, independent of the actual location or description of the data, and each instruction is concerned only with a logical function, i.e., ADD, SUBTRACT, COMPARE, etc.

The system in this example operates with an 8-bit byte and has a maximum of 256 data fields. The maximum alphameric field size is 128 bytes and decimal fields have a maximum of (a) 15 digits to the left of the decimal point, and (b) 7 digits to the right of the decimal point. Table entries have the following format: 3-byte Table Entry.

BIT POSITIONS 0 7 8 15 16 23.

BITS 0-15 Storage address of the data field

16-23 Attributes of the data field

- if bit 16 is 0, the field is alphameric and

bits 17-23 permit a length range of 1 to 128

bytes. The length value is field length -1.

- if bit 16 is 1, the field is numeric and bits

17-19 indicate the number of digits to the

right of the decimal point in the range 0-7,

and bits 20-23 indicate the number of digits

to the left of the decimal point in the range

0-15.

The normal instruction size in this system is either three or four bytes, consisting of an Operation Code and two or three 1-byte operands.

In the figure, the instruction ADD A to B requires 3 bytes, and ADD A to B with the results in C requires 4 bytes. Since the attribute portions of the table entries specify the location of the decimal points in the data fields, the processor performs decimal alignment during the operation. In either case, the result is placed in the final operand field. Since the table entries contain both the address and the attributes of the data fields, instructions need only refer to the table to find the information to properly process the field. Th...