Multioperand Decimal Adder Using Binary Carry-Save Addition

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Solution Overview

Problem

Computers typically support only binary arithmetic, leading to inefficiencies and errors when handling decimal numbers, as they require conversion between binary and decimal formats, which is computationally intensive and prone to errors, especially in financial and real-world applications.

Innovation Solution

The development of multioperand decimal adders using binary carry-save addition (CSA) techniques with speculative correction methods to perform high-speed decimal arithmetic, enabling fast and efficient addition and subtraction of multiple decimal operands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If binary arithmetic is used in hardware, then computational speed and efficiency are improved, but accuracy and reliability deteriorate due to conversion errors and inability to represent decimal numbers exactly

Engineering Contradiction:
Improvecomputational speedVSAvoidaccuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the numerical representation parameter from binary to decimal by implementing a decimal adder circuit that directly processes decimal numbers. The adder uses BCD (Binary Coded Decimal) representation with 4-bit groups for each decimal digit, allowing exact decimal arithmetic without conversion errors while maintaining hardware-based computational speed.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If decimal to binary conversion is performed, then decimal numbers can be processed, but computational overhead and processing time increase significantly

Engineering Contradiction:
Improvedecimal processing capabilityVSAvoidconversion time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent extracts the conversion step from the processing pipeline by implementing dedicated decimal arithmetic circuitry. The decimal adder directly operates on decimal inputs in BCD format, eliminating the time-consuming decimal-to-binary conversion step entirely while maintaining the ability to process decimal numbers.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If software packages are used for decimal arithmetic, then accuracy is improved, but processing speed deteriorates by hundreds to thousands of times compared to binary operations

Engineering Contradiction:
Improvedecimal arithmetic accuracyVSAvoidprocessing speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the software-based decimal arithmetic system with a hardware-based decimal adder circuit. This substitution implements decimal addition logic directly in electronic circuitry using BCD representation, achieving both the accuracy of software decimal arithmetic and the speed of hardware binary operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If two operand BCD addition with correction is used, then decimal addition can be performed, but computational speed deteriorates due to multiple correction steps

Engineering Contradiction:
Improvedecimal addition capabilityVSAvoidaddition speed
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent applies preliminary action by pre-computing and hardwiring the correction logic for BCD addition. The circuit includes dedicated logic that automatically detects when correction is needed (when sum exceeds 9) and applies the correction value of 6 through hardwired connections, eliminating the need for iterative correction steps and significantly speeding up the addition process.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS7743084B2Processing unit having multioperand decimal addition
Publication Date: 2010.06.22 WISCONSIN ALUMNI RES FOUND
  • US7743084B2 patent drawing
  • US7743084B2 patent drawing
  • US7743084B2 patent drawing

AI summary

A multi-operand decimal adder is described that performs addition on multiple binary coded decimal (BCD) operands. The multi-operand decimal adder uses binary carry-save adders to produce intermediate sums and carries, and outputs a decimal result based on the intermediate sums and carries. In various configurations, the multi-operand decimal adder may perform speculative or non-speculative binary carry-save addition. The multioperand decimal adders achieve a reasonable critical path. As a result, the decimal adders and the techniques described herein may be especially suited for numerically intensive commercial applications, such as spreadsheet or financial applications where large amounts of decimal data typically need to be processed quickly.