Patent US3609708A successfully refreshed from Google Patents.
US3609708A
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Optimized read only memory using tag bits
Assignee: Texas Instruments Inc
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Filing: 1968-12-30
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Granted: 1971-09-28
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Expires: 1988-12-30
Abstract
Abstract Word length limitations on ''''read only'''' memories due to limited driving capability of a single word driver and the limitations upon the number of words which can be stored due to the limited number of inputs to OR gates at the memory output are minimized by complementing each row in the memory matrix and each column in the memory matrix when the number of ones in a given row or column is greater than one-half the number of bits in the row or column respectively and storing a first set of tag bits representative of the rows complemented and the second set of tag bits representative of the columns complemented. Means are provided for reading from the sets of tag bits when reading data represented by bits in the memory rows and columns.
Inventors
- 👤 Harvey G Cragon
- 👤 William D Kastner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:26
CPC Classifications
G; G11; G11C; G11C17/00; G11C17/06
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
304 words
In a read only memory wherein the presence or absence of an element in a storage matrix signifies a one and a zero respectively, means for enhancing the driving capability of a single word driver and enhancing the number of words which can be stored which comprises: a. means representing the complement of each bit in a given word where the number of said elements in said given word exceeds one-half the number of word bits, b. means readable with said word for storing an index to the words whose bits are complemented; c. means representing the complement of each bit in each column of said matrix in which the number of said elements exceeds one-half the number of bits in said a given column; d. means readable with each said column for storing an index to the columns whose bits are complemented; e. output OR gates in number corresponding with the number of bits in said words have inputs connected to each word line where one state is to be decoded, f. a tag bit OR gate connected to each word line where the word has been complemented, g. first exclusive OR gates each having one input supplied by one of said output OR gates, a tag exclusive OR gate having one input supplied by said tag bit OR gate, h. said first and tag exclusive OR gates each having a second input connected to a bit control word line for each column having bits complemented, and i. second exclusive OR gates in number corresponding to the number of bits in each of said words each having one input supplied by the output of exclusive OR gates corresponding to said columns and all having a second input supplied by the output of the exclusive OR gate connected to said tag bit OR gate.
Claim 2
Dependent Claim
304 words
In a read only memory wherein the presence or absence of an element in a storage matrix signifies a one and a zero respectively, means for enhancing the driving capability of a single word driver and enhancing the number of words which can be stored which comprises: a. means representing the complement of each bit in a given word where the number of said elements in said given word exceeds one-half the number of word bits, b. means readable with said word for storing an index to the words whose bits are complemented; c. means representing the complement of each bit in each column of said matrix in which the number of said elements exceeds one-half the number of bits in said a given column; d. means readable with each said column for storing an index to the columns whose bits are complemented; e. output OR gates in number corresponding with the number of bits in said words have inputs connected to each word line where one state is to be decoded, f. a tag bit OR gate connected to each word line where the word has been complemented, g. first exclusive OR gates each having one input supplied by one of said output OR gates, a tag exclusive OR gate having one input supplied by said tag bit OR gate, h. said first and tag exclusive OR gates each having a second input connected to a bit control word line for each column having bits complemented, and i. second exclusive OR gates in number corresponding to the number of bits in each of said words each having one input supplied by the output of exclusive OR gates corresponding to said columns and all having a second input supplied by the output of the exclusive OR gate connected to said tag bit OR gate.
Claim 3
Dependent Claim
180 words
In a read only memory wherein the presence or absence of an element in a storage matrix signifies a one and a zero respectively, means for enhancing the driving capability of a single word driver and enhancing the number of words which can be stored which comprises: a. means representing the complement of each bit in a given word where the number of said elements in said given word exceeds one-half the number of word bits, b. means readable with said word for storing an index to the words whose bits are complemented; c. means representing the complement of each bit in each column of said matrix in which the number of said elements exceeds one-half the number of bits in said a given column, and d. means readable with each said column for storing an index to the columns whose bits are complemented, wherein the means representing the complement of each bit in each column of said matrix includes output OR gates having connections selectively made to the output or its complement to provide a mechanized bit control word.
Claim 4
Dependent Claim
180 words
In a read only memory wherein the presence or absence of an element in a storage matrix signifies a one and a zero respectively, means for enhancing the driving capability of a single word driver and enhancing the number of words which can be stored which comprises: a. means representing the complement of each bit in a given word where the number of said elements in said given word exceeds one-half the number of word bits, b. means readable with said word for storing an index to the words whose bits are complemented; c. means representing the complement of each bit in each column of said matrix in which the number of said elements exceeds one-half the number of bits in said a given column, and d. means readable with each said column for storing an index to the columns whose bits are complemented, wherein the means representing the complement of each bit in each column of said matrix includes output OR gates having connections selectively made to the output or its complement to provide a mechanized bit control word.
Claim 5
Dependent Claim
155 words
In a read only computer memory matrix where the presence or absence of an element in a row or column of said matrix represents a one or a zero respectively, the method of enhancing the cooperation between said matrix and its drive and output system which comprises: a. complementing all bits in each row and in each column of said matrix until the number of said elements in any given row or column is less than one-half the number of bits in any row or column, b. storing a first set of tag bits representative of the rows complemented, c. storing a second set of tag bits representative of the columns complemented, and d. upon reading data represented by said ones and zeros from memory, reading from said sets of tag Bits those tag bits which are representative of the rows and columns read from memory whereby correcting data read to represent intended memory data.
Claim 6
Dependent Claim
155 words
In a read only computer memory matrix where the presence or absence of an element in a row or column of said matrix represents a one or a zero respectively, the method of enhancing the cooperation between said matrix and its drive and output system which comprises: a. complementing all bits in each row and in each column of said matrix until the number of said elements in any given row or column is less than one-half the number of bits in any row or column, b. storing a first set of tag bits representative of the rows complemented, c. storing a second set of tag bits representative of the columns complemented, and d. upon reading data represented by said ones and zeros from memory, reading from said sets of tag Bits those tag bits which are representative of the rows and columns read from memory whereby correcting data read to represent intended memory data.
Claim 7
Dependent Claim
17 words
The method of claim 3 wherein signals read from memory are reconstructed to compensate for said complementing.
Claim 8
Dependent Claim
100 words
In a read only computer memory matrix where the presence or absence of an element signifies a one or a zero respectively, the method of enhancing the driving capability of single word drivers for reading from said memory, which comprises: a. complementing all bits in each memory word wherein the number of said elements is greater than one-half the number of word bits, b. storing in said memory a tag bit for each of said words which tag bit is indicative of said complementing, and c. with the reading of each of said words from memory, reading said tag bit.
Claim 9
Dependent Claim
100 words
In a read only computer memory matrix where the presence or absence of an element signifies a one or a zero respectively, the method of enhancing the driving capability of single word drivers for reading from said memory, which comprises: a. complementing all bits in each memory word wherein the number of said elements is greater than one-half the number of word bits, b. storing in said memory a tag bit for each of said words which tag bit is indicative of said complementing, and c. with the reading of each of said words from memory, reading said tag bit.
Claim 10
Dependent Claim
21 words
The method of claim 5 where, upon reading from said memory matrix selected bits are recomplemented to compensate for said complementing.
Claim 11
Dependent Claim
126 words
In a read only computer memory matrix wherein the presence or absence of an element in any column of said matrix represents a one or a zero respectively, the method of enhancing the number of words that can be stored in said memory without exceeding the number of inputs of OR gates at the memory output which comprises: a. complementing all bits in each said column wherein the number of said elements exceeds more than one-half the number of bits in each said column, b. storing in said memory a tab bit for each said column which bit is representative of said complementing, and c. with the reading of each said column from said matrix, reading said tag bit, d. and reconstructing the original memory data.
Claim 12
Dependent Claim
126 words
In a read only computer memory matrix wherein the presence or absence of an element in any column of said matrix represents a one or a zero respectively, the method of enhancing the number of words that can be stored in said memory without exceeding the number of inputs of OR gates at the memory output which comprises: a. complementing all bits in each said column wherein the number of said elements exceeds more than one-half the number of bits in each said column, b. storing in said memory a tab bit for each said column which bit is representative of said complementing, and c. with the reading of each said column from said matrix, reading said tag bit, d. and reconstructing the original memory data.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |