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 Title: |
US4999803:
Floating point arithmetic system and method
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Turrini, Silvio; Trieste, Italy
Leonard, Judson S.; Waban, MA
Jouppi, Norman P.; Palo Alto, CA
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| Assignee: |
Digital Equipment Corporation, Maynard, MA
other patents from DIGITAL EQUIPMENT CORPORATION (147695) (approx. 2,345)
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| Published / Filed: |
1991-03-12
/ 1989-06-29
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| Application Number: |
US1989000374164
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| IPC Code: |
Advanced:
G06F 7/485;
G06F 7/50;
Core:
more...
IPC-7:
G06F 7/38;
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| ECLA Code: |
G06F7/485; S06F207/38A6P;
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| U.S. Class: |
Current:
708/505;
Original:
364/748;
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| Field of Search: |
364/748,715.04,715.08
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| Priority Number: |
| 1989-06-29 |
US1989000374164 |
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| Abstract: |
System and method for reducing the processing time or latency of floating point arithmetic operations by eliminating the need to complement a negative result produced by a subtraction operation. Each of two numbers is subtracted from the other in simultaneous parallel subtraction operations to produce one answer which is positive and one answer which is negative. The answer which is positive is selected as the result of the operation.
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| Attorney, Agent or Firm: |
Flehr, Hohbach, Test, Albritton & Herbert ;
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| Primary / Asst. Examiners: |
Shaw, Dale M.; Mai, Tan V.
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| INPADOC Legal Status: |
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| Family: |
None
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First Claim:
Show all 4 claims |
We claim:
1. In a system for performing floating point arithmetic with first and second numbers each having a mantissa and an exponent:
- a. means for comparing the exponents of the two numbers;
- b. a first data path having an alignment shifter for shifting the mantissa of one of the numbers by more than one place to provide numbers with aligned mantissas and equal exponents, an adder/subtractor for combining the aligned mantissas, and means for normalizing the output from the adder/subtractor by shifting its mantissa by no more than one place;
- c. a second data path having means for shifting the mantissa of one of the two numbers no more than one place to provide numbers with aligned mantissas and equal exponents, a pair of subtractors in parallel paths for simultaneously subtracting the mantissa of the first number from the mantissa of the second number and the mantissa of the second number from the mantissa of the first number to produce one result which is positive and one result which is negative, means for selecting the positive result, and means for normalizing the selected result by shifting its mantissa by more than one place; and
- d. means for selecting between the normalized results from the two data paths.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 15 U.S. patent(s) that reference this one
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