US4041475A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Computer memory
Assignee: Massachusetts Institute of Technology
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Filing: 1975-07-16
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Granted: 1977-08-09
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Expires: 1995-07-16
Abstract
Abstract A memory system is shown in which communication to and from memory cells is effected by optical beams. Memory cells are shown employing elements with negative resistance and operating in either of two stable modes. Other memory cells are shown employing subharmonic oscillators operating in either of two phase relationships. The memory cells and systems permit extremely fast operation.
Inventors
- 👤 Ali Javan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:08
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/21; G11C11/42
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
363 words
In a memory system having an assembly of memory cells with identifying address values, each cell capable of assuming alternatively either of two states, the states defining the value of information stored in the cell, the improvement comprising in combination an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising electrical circuitry having two alternative stable states, and input-output means, connected to said circuitry, said means being responsive to incident optical radiation having two distinct alternative characterizations and producing two alternative electrical effects in correspondence thereto, said means being responsive to the operating state of said circuitry to emit radiation indicating the operating state of said circuitry, said circuitry being arranged and connected so that when said input-output means is stimulated by directionally-controlled optical radiation having a first of said distinct charcterizations said circuitry assumes a first of said stable states in response to the first of said effects and when said means is stimulated by optical radiation of a second of said characterizations said circuitry assumes a second of said operating states in response to the second of said effects, a radiation processor arranged to send directionallycontrolled optical radiation to and receive radiation from said array, said processor having data input, data output, and adress input, said processor arranged to operate in a write-in mode generating a beam of optical radiation directed selectively to the one of said cells corresponding to the value of an addressing signal received on said address input, the radiation of said beam having two distinctive alternative characterizations corresponding to the value of a data signal received on said data input, said processor including a radiation receiver arranged to operate in a read-out mode responding selectively to radiation from the one of said cells corresponding to the value of an addressing signal received on said address input and to emit on said data output an electrical signal of value corresponding to the characterization of the received radiation, said radiation processor including a lens system focussing optical radiation on a selected one of said cells, and said array being supported on a surface of a lens of said lens system.
Claim 2
Dependent Claim
363 words
In a memory system having an assembly of memory cells with identifying address values, each cell capable of assuming alternatively either of two states, the states defining the value of information stored in the cell, the improvement comprising in combination an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising electrical circuitry having two alternative stable states, and input-output means, connected to said circuitry, said means being responsive to incident optical radiation having two distinct alternative characterizations and producing two alternative electrical effects in correspondence thereto, said means being responsive to the operating state of said circuitry to emit radiation indicating the operating state of said circuitry, said circuitry being arranged and connected so that when said input-output means is stimulated by directionally-controlled optical radiation having a first of said distinct charcterizations said circuitry assumes a first of said stable states in response to the first of said effects and when said means is stimulated by optical radiation of a second of said characterizations said circuitry assumes a second of said operating states in response to the second of said effects, a radiation processor arranged to send directionallycontrolled optical radiation to and receive radiation from said array, said processor having data input, data output, and adress input, said processor arranged to operate in a write-in mode generating a beam of optical radiation directed selectively to the one of said cells corresponding to the value of an addressing signal received on said address input, the radiation of said beam having two distinctive alternative characterizations corresponding to the value of a data signal received on said data input, said processor including a radiation receiver arranged to operate in a read-out mode responding selectively to radiation from the one of said cells corresponding to the value of an addressing signal received on said address input and to emit on said data output an electrical signal of value corresponding to the characterization of the received radiation, said radiation processor including a lens system focussing optical radiation on a selected one of said cells, and said array being supported on a surface of a lens of said lens system.
Claim 3
Dependent Claim
232 words
In a memory system having an assembly of memory cells with identifying address values, each cell capable of assuming alternatively either of two states, the states defining the value of information stored in the cell, the improvement comprising an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising electrical circuitry having two alternative stable states, and input-output means, connected to said circuitry, said means being responsive to incident optical radiation having two distinct alternative characterizations and producing two alternative electrical effects in correspondence thereto, said means being responsive to the operating state of said circuitry to emit radiation indicating the operating state of said circuitry, said circuitry being arranged and connected so that when said input-output means is stimulated by directionally-controlled optical radiation having a first of said distinct characterizations said circuitry assumes a first of said stable states in response to the first of said effects and when said means is stimulated by optical radiation of a second of said characterizations said circuitry assumes a second of said operating states in response to the second of said effects, and means for providing operating power for said cells transmitted thereto by optical radiation, and said substrate being transparent to said incident optical radiation, and said operating power radiation and said radiation of two characterizations being incident on opposite sides of said memory array.
Claim 4
Dependent Claim
232 words
In a memory system having an assembly of memory cells with identifying address values, each cell capable of assuming alternatively either of two states, the states defining the value of information stored in the cell, the improvement comprising an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising electrical circuitry having two alternative stable states, and input-output means, connected to said circuitry, said means being responsive to incident optical radiation having two distinct alternative characterizations and producing two alternative electrical effects in correspondence thereto, said means being responsive to the operating state of said circuitry to emit radiation indicating the operating state of said circuitry, said circuitry being arranged and connected so that when said input-output means is stimulated by directionally-controlled optical radiation having a first of said distinct characterizations said circuitry assumes a first of said stable states in response to the first of said effects and when said means is stimulated by optical radiation of a second of said characterizations said circuitry assumes a second of said operating states in response to the second of said effects, and means for providing operating power for said cells transmitted thereto by optical radiation, and said substrate being transparent to said incident optical radiation, and said operating power radiation and said radiation of two characterizations being incident on opposite sides of said memory array.
Claim 5
Dependent Claim
204 words
A memory system having an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising circuitry with an element having a negative resistance characteristic connected in series with a load resistor across a voltage source, said circuitry in the absence of an optically generated input operating stably alternatively at either a first or a second point of its characteristic, said two operating points being associated respectively with the value of information stored in the cell, input means connected to said circuitry and responsive to momentary optical radiation incident at either a first or a second area on said cell, said first and second areas being sufficiently spaced to avoid diffractive interaction, said input means operative in response to momentary incidence of optical radiation on said first area to coerce said circuitry to its first operating point and in response to momentary incidence of optical radition on said second area to coerce said circuitry to its second operating point, and an antenna connected to said circuitry to radiate when said coercion results in switching due to the coerced operating point differing from the operating point prior to coercion thereby to enable determination of the prior operating point.
Claim 6
Dependent Claim
204 words
A memory system having an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising circuitry with an element having a negative resistance characteristic connected in series with a load resistor across a voltage source, said circuitry in the absence of an optically generated input operating stably alternatively at either a first or a second point of its characteristic, said two operating points being associated respectively with the value of information stored in the cell, input means connected to said circuitry and responsive to momentary optical radiation incident at either a first or a second area on said cell, said first and second areas being sufficiently spaced to avoid diffractive interaction, said input means operative in response to momentary incidence of optical radiation on said first area to coerce said circuitry to its first operating point and in response to momentary incidence of optical radition on said second area to coerce said circuitry to its second operating point, and an antenna connected to said circuitry to radiate when said coercion results in switching due to the coerced operating point differing from the operating point prior to coercion thereby to enable determination of the prior operating point.
Claim 7
Dependent Claim
205 words
A memory system having an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising circuitry with an element having a negative resistance characteristic connected in series with a load resistor across a voltage source, said circuitry in the absence of an optically generated input operating stably alternatively at either a first or a second point of its characteristic, said two operating points being associated respectively with the value of information stored in the cell, input means connected to said circuitry and responsive to momentary optical radiation incident at either a first or a second area on said cell, said first and second areas being sufficiently spaced to avoid diffractive interaction, said input means operative in response to momentary incidence of optical radiation on said first area to coerce said circuitry to its first operating point and in response to momentary incidence of optical radiation on said second area to coerce said circuitry to its second operating point, and output means connected to said circuitry and responsive to incidence of optical radiation at a third area of said cell to emit a signal indicative of the operating point of said circuitry while leaving said operating point unchanged.
Claim 8
Dependent Claim
205 words
A memory system having an array of memory cells spatially arranged on a substrate in accordance with identifying address values, each cell comprising circuitry with an element having a negative resistance characteristic connected in series with a load resistor across a voltage source, said circuitry in the absence of an optically generated input operating stably alternatively at either a first or a second point of its characteristic, said two operating points being associated respectively with the value of information stored in the cell, input means connected to said circuitry and responsive to momentary optical radiation incident at either a first or a second area on said cell, said first and second areas being sufficiently spaced to avoid diffractive interaction, said input means operative in response to momentary incidence of optical radiation on said first area to coerce said circuitry to its first operating point and in response to momentary incidence of optical radiation on said second area to coerce said circuitry to its second operating point, and output means connected to said circuitry and responsive to incidence of optical radiation at a third area of said cell to emit a signal indicative of the operating point of said circuitry while leaving said operating point unchanged.
Claim 9
Dependent Claim
36 words
Apparatus as claimed in claim 4, said output means including an oscillator and an antenna, said oscillator connected to oscillate only when said circuitry is in its first operating point and said third area is illuminated.
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) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |