US3678259A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Asynchronous logic for determining number of leading zeros in a digital word
Assignee: Link Flight Simulation Corp
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Filing: 1970-07-28
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Granted: 1972-07-18
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Expires: 1990-07-28
Abstract
Abstract This invention relates to an asynchronous device for counting the number of consecutive leading zeros, starting with the most significant digit, in a digital word. Such a device is useful in generating shift and exponent modification information in floating-point digital computers and in generating information for overflow detection in fixed-point digital computers. The device comprises a plurality of gates, one for each digit in the binary word, which are so interconnected that they pass information only when the particular digit signal applied thereto is a zero and only when all of the higher order (more significant) digits are also zeros. The outputs of the gates are applied to a plurality of adders where they are counted, and the total is presented at the output. The total can than be used to control a shifter for properly locating the binary point in the word, and to provide information for exponent modification, or to provide information for overflow detection.
Inventors
- 👤 Lesile T Kyser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:01
CPC Classifications
G; G06; G06F; G06F7/00; G06F7/74; G06F7/38; G06F7/48; G06F7/483; G06F7/499; G06F7/49905; G06F7/4991; G06F7/49936
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
89 words
A device for counting the leading zeros in a digital word, said device comprising a plurality of gates, said plurality comprising one gate for eacH digit of the word to be processed, means for applying to the inputs of each of said gates all of the digits more significant than that gate, and means for summing the outputs of all of said gates to produce a single number which represents the total of the zeros in said word which occupy consecutive positions more significant than the most significant nonzero.
Claim 2
Independent Claim
89 words
A device for counting the leading zeros in a digital word, said device comprising a plurality of gates, said plurality comprising one gate for eacH digit of the word to be processed, means for applying to the inputs of each of said gates all of the digits more significant than that gate, and means for summing the outputs of all of said gates to produce a single number which represents the total of the zeros in said word which occupy consecutive positions more significant than the most significant nonzero.
Claim 3
Dependent Claim
145 words
Apparatus for counting the number of leading zeros in the more significant digit positions of a digital word which precede the first nonzero digit, said apparatus comprising a gate for each digit of the word to be tested, each of said gates having more than one input and being adapted to pass a signal when all of the signals applied to all of its inputs represent ones, said gates and digits being arranged in groups, means for connecting all of the digits in a group to the inputs of the gate having least significance in the group, means for applying to the input of the gate in each group of highest significance the output from the gate of lowest significance of the group having immediate higher significance, and inversion means connected to the inputs of each gate to which the digit is to be applied.
Claim 4
Dependent Claim
145 words
Apparatus for counting the number of leading zeros in the more significant digit positions of a digital word which precede the first nonzero digit, said apparatus comprising a gate for each digit of the word to be tested, each of said gates having more than one input and being adapted to pass a signal when all of the signals applied to all of its inputs represent ones, said gates and digits being arranged in groups, means for connecting all of the digits in a group to the inputs of the gate having least significance in the group, means for applying to the input of the gate in each group of highest significance the output from the gate of lowest significance of the group having immediate higher significance, and inversion means connected to the inputs of each gate to which the digit is to be applied.
Claim 5
Dependent Claim
39 words
The apparatus defined in claim 2 further including means for determining the number of gates which open, said determining means comprising a plurality of adders connected to the outputs from said gates to add all of the gate outputs.
Claim 6
Dependent Claim
89 words
The apparatus defined in claim 3 wherein each of said adders has at least two inputs and two outputs, means for connecting the two inputs of each adder the outputs from gates and outputs from other adders having mathematical significance of the same power, and means for connecting the outputs from the adders in the various levels to inputs of the next higher level adders to produce a final sum which represents the total number of zeros in the digital word being tested which precede the first nonzero digit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-18 | 1976-01-17 | 1976-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-18 | 1980-01-17 | 1980-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-18 | 1984-01-17 | 1984-07-18 | $7700.00 | Window Closed / Lapsed |